Which of the following are quadratic equations in x?
x2 - x + 3 = 0
The given equation is a quadratic equation.
Explanation - It is of degree 2, it is in the form (a ≠ 0, a, b, c are real numbers)
where a = 1, b = - 1, c = 3.
Which of the following are quadratic equations in x?
The given equation equation is a quadratic equation.
Explanation - It is of degree 2, it is in the form (a ≠ 0, a, b, c are real numbers)
where a = 2, b = , c =
The given equation is a quadratic equation.
Explanation - It is of degree 2, it is in the form (a ≠ 0, a, b, c are real numbers)
where a = √2, b = 7, c = 5√2.
Which of the following are quadratic equations in x?
The given equation is a quadratic equation.
Explanation - It is of degree 2, it is in the form (a ≠ 0, a, b, c are real numbers)
where a = 1/3 , b = 1/5, c = - 2.
Which of the following are quadratic equations in x?
The given equation is not a quadratic equation.
Explanation - It is not in the form of because it has an extra term - √x with power 1/2
Which of the following are quadratic equations in x?
The given equation is a quadratic equation.
Explanation - Given
On solving the equation it gets reduced to; ; It is of degree 2 and it is in the form (a ≠ 0, a, b, c are real numbers) where a = 1, b = - 3, c = - 6.
Which of the following are quadratic equations in x?
The given equation is not a quadratic equation.
Explanation - Given
On getting reduced it becomes, it has degree = 3, it is not in the form
(a ≠ 0, a, b, c are real numbers).
Which of the following are quadratic equations in x?
The given equation is not a quadratic equation.
Explanation - Given
On getting reduced it becomes ;
It is not in the form ax2 + bx + c = 0 (a ≠ 0, a, b, c are real numbers)
Which of the following are quadratic equations in x?
(x + 2)3 = x3 – 8
The given equation is a quadratic equation.
Explanation Given
On getting reduced it becomes
=
Now, using
where a = 6, b = 12, c = 16
It is in the form (a ≠ 0, a, b, c are real numbers)
Which of the following are quadratic equations in x?
2x + 3)(3x + 2) = 6(x - 1)(x - 2)
The given (2x + 3)(3x + 2) = 6(x - 1)(x - 2)equation is not a quadratic equation.
Explanation - Given (2x + 3)(3x + 2) = 6(x - 1)(x - 2)
On getting reduced it becomes
It is not in the form (a ≠ 0, a, b, c are real numbers)
Which of the following are quadratic equations in x?
The given equation is not a quadratic equation.
Explanation - Given
On getting reduced it becomes -
It is not in the form (a ≠ 0, a, b, c are real numbers)
Which of the following are the roots of 3x2 + 2x - 1 = 0 ?
(i) - 1 (ii) 1/3 (iii) –1/2
(i) - 1 is the root of given equation.
Explanation - Substituting value - 1 in LHS
=
= 3 - 2 - 1
= 3 - 3 = 0 = RHS
Value satisfies the equation or LHS = RHS.
(ii) is the root of the given euation
Explanation - Substituting value in LHS
=
=
= 1 - 1 = 0 = RHS
Value satisfies the equation or LHS = RHS.
(iii) is not the root of given equation
Explanation - Substituting value in LHS
=
=
= ≠ 0 ≠ RHS
Value does not satisfy the equation or LHS ≠ RHS.
Find the value of k for which x = 1 is a root of the equation x2 + kx + 3 = 0. Also, find the other root.
Given x = 1 is a root of the equation x2 + kx + 3 = 0 it means it satisfies the equation.
Substituting x = 1 in equation -
12 + k(1) + 3 = 0
Putting the value of k in the given equation : x2 + kx + 3 = 0
This reduced to the quadratic equation x2 - 4x + 3 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
= 1.3
= 3
And either of their sum or difference = b
= - 4
Thus the two terms are - 1 and - 3
Sum = - 1 - 3 = - 4
Product = - 1. - 3 = 3
x(x-1)-3(x-1) = 0
(x-1)(x-3) = 0
x = 1 or x = 3
Thus other root is 3.
Find the values of a or b for which x = 3/4 or x = - 2 are the roots of the equation
ax2 + bx – 6 = 0
Given x = 3/4 or x = - 2 are the roots of the equation
Putting in the equation gives -
;
9a + 12b-96 = 0
3a + 4b-32 = 0 - - - - - - - - - - - - - - - (1)
putting x = - 2 in equation gives
4a-2b-6 = 0
2a-b-3 = 0
2a-3 = b - - - - - - - - - - - (2)
Substituting (2) in (1)
3a + 4(2a-3)-32 = 0
⇒ 11a-44 = 0
⇒ a = 4
⇒ b = 2(4)-3 = 5
Thus for a = 4 or b = 5; or x = - 2 are the roots of the equation
Solve each of the following quadratic equations:
(2x-3) (3x + 1) = 0
(2x-3) (3x + 1) = 0
2x(3x + 1)-3(3x + 1) = 0 taking common from first two terms and last two terms
(2x-3)(3x + 1) = 0
(2x-3) = 0 or (3x + 1) = 0
x = 3/2 or x = (-1)/3
Roots of equation are 3/2, (-1)/3
Solve each of the following quadratic equations:
4x2 + 5x = 0
x(4x + 5) = 0 (On taking x common)
x = 0 or (4x + 5) = 0
x = (-5)/4
Roots of equation are 0, (-5)/4
Solve each of the following quadratic equations:
3x2 – 243 = 0
x = √81
Roots of equation are 9, - 9
Solve each of the following quadratic equations:
2x2 + x - 6 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 2; b = 1; c = -6
= 2. - 6
= - 12
And either of their sum or difference = b
= 1
Thus the two terms are 4 and - 3
Difference = 4 - 3 = 1
Product = 4. - 3 = - 12
2x(x + 2)-3(x + 2) = 0
(2x-3)(x + 2) = 0
(2x-3) = 0 or (x + 2) = 0
x = 3/2, x = -2
Roots of equation are 3/2, - 2
Solve each of the following quadratic equations:
x2 + 6x + 5 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1, b = 6, c = 5
= 1.5 = 5
And either of their sum or difference = b
= 6
Thus the two terms are 1 and 5
Sum = 5 + 1 = 6
Product = 5.1 = 5
x(x + 1) + 5(x + 1) = 0
(x + 1)(x + 5) = 0
(x + 1) = 0 or (x + 5) = 0
x = -1, x = -5
Roots of equation are - 1, - 5
Solve each of the following quadratic equations:
9x2 - 3x - 2 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 9; b = -3; c = -2
= 9. - 2 = - 18
And either of their sum or difference = b
= - 3
Thus the two terms are - 6 and 3
Sum = - 6 + 3 = - 3
Product = - 6.3 = - 18
3x(3x-2) + 1(3x-2) = 0
(3x + 1)(3x-2) = 0
(3x + 1) = 0 or (3x-2) = 0
x = (-1)/3 or x = 2/3
Roots of equation are (-1)/3, 2/3
Solve each of the following quadratic equations:
x2 + 12x + 35 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1; b = 12; c = 35
= 1.35 = 35
And either of their sum or difference = b
= 12
Thus the two terms are 7 and 5
Sum = 7 + 5 = 12
Product = 7.5 = 35
x(x + 7) + 5(x + 7) = 0
(x + 5)(x + 7) = 0
(x + 5) = 0 or (x + 7) = 0
x = -5 or x = -7
Roots of equation are - 5, - 7
Solve each of the following quadratic equations:
x2 = 18x – 77
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1; b = -18; c = 77
= 1.77 = 77
And either of their sum or difference = b
= - 18
Thus the two terms are - 7 and - 11
Sum = - 7 - 11 = - 18
Product = - 7. - 11 = 77
x(x-7)-11(x-7) = 0
(x-7)(x-11) = 0
(x-7) = 0 or (x-11) = 0
x = 7 or x = 11
Roots of equation are 7, 11
Solve each of the following quadratic equations:
6x2 + 11x + 3 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 6; b = 11; c = 3
= 6.3 = 18
And either of their sum or difference = b
= 11
Thus the two terms are 9 and 2
Sum = 9 + 2 = 11
Product = 9.2 = 18
3x(2x + 3) + 1(2x + 3) = 0
(3x + 1)(2x + 3) = 0
(3x + 1) = 0 or (2x + 3) = 0
x = (-1)/3 or x = (-3)/2
Roots of equation are ,
Solve each of the following quadratic equations:
6x2 + x - 12 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 6; b = 1; c = -12
= 6. - 12 = - 72
And either of their sum or difference = b
= 1
Thus the two terms are 9 and - 8
Difference = 9 - 8 = 1
Product = 9. - 8 = - 72
3x(2x + 3)-4(2x + 3) = 0
(2x + 3)(3x-4) = 0
(2x + 3) = 0 or (3x-4) = 0
x = (-3)/2 or x = 4/3
Roots of equation are ,
Solve each of the following quadratic equations:
3x2 - 2x - 1 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 3; b = -2; c = -1
= 3. - 1 = - 3
And either of their sum or difference = b
= - 2
Thus the two terms are - 3 and 1
Difference = - 3 + 1 = - 2
Product = - 3.1 = - 3
3x(x-1) + 1(x-1) = 0
(x-1)(3x + 1) = 0
(x-1) = 0 or (3x + 1) = 0
x = 1 or x = (-1)/3
Roots of equation are 1, (-1)/3
Solve each of the following quadratic equations:
4x2 - 9x = 100
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 4; b = -9 ; c = -100
= 4. - 100 = - 400
And either of their sum or difference = b
= - 9
Thus the two terms are - 25 and 16
Difference = - 25 + 16 = - 9
Product = - 25.16 = - 400
x(4x-25) + 4(4x-25) = 0
(4x-25)(x + 4) = 0
(4x-25) = 0 or (x + 4) = 0
x = 25/4 or x = -4
Roots of equation are 25/4, - 4
Solve each of the following quadratic equations:
15x2 - 28 = x
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 15 ; b = -1; c = -28
= 15. - 28 = - 420
And either of their sum or difference = b
= - 1
Thus the two terms are - 21 and 20
Difference = - 21 + 20 = - 1
Product = - 21.20 = - 420
3x(5x-7) + 4(5x-7) = 0
(5x-7)(3x + 4) = 0
(5x-7) = 0 or (3x + 4) = 0
x = 7/5 or x = (-4)/3
Roots of equation are 7/5, - 4/3
Solve each of the following quadratic equations:
4 - 11x = 3x2
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 3; b = 11 ;c = -4
= 3. - 4 = - 12
And either of their sum or difference = b
= 11
Thus the two terms are 12 and - 1
Difference = 12 - 1 = 11
Product = 12. - 1 = - 12
3x(x + 4)-1(x + 4) = 0
(x + 4)(3x-1) = 0
(x + 4) = 0 or (3x-1) = 0
x = -4 or x = 1/3
Roots of equation are - 4, 1/3
Solve each of the following quadratic equations:
48x2 - 13x - 1 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 48; b = -13 ;c = -1
= 48× - 1 = - 48
And either of their sum or difference = b
= - 13
Thus the two terms are - 16 and 3
Difference = - 16 + 3 = - 13
Product = - 16.3 = - 48
16x(3x-1) + 1(3x-1) = 0
(16x + 1)(3x-1) = 0
(16x + 1) = 0 or (3x-1) = 0
x = (-1)/6 or x = 1/3
Roots of equation are
Solve each of the following quadratic equations:
x2 + 2√2 x – 6 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1; b = 2√2; c = -6
= 1. - 6 = - 6
And either of their sum or difference = b
= 2√2
Thus the two terms are 3√2 and -√2
Difference = 3√2-√2 = 2√2
Product = 3√2.-√2 = 3.-2 = -6
using
x(x + 3√2)-√2(x + 3√2) = 0
(x-√2)(x + 3√2) = 0
(x-√2) = 0 or (x + 3√2) = 0
x = √2 or x = -3√2
Roots of equation are √2 or -3√2
Solve each of the following quadratic equations:
√3x2 + 10x + 7√3 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = √3 ;b = 10; c = 7√3
= √3.7√3 = 21
(using 3 = √3×√3)
And either of their sum or difference = b
= 10
Thus, the two terms are 7 and 3
Sum = 7 + 3 = 10
Product = 7.3 = 21
(using )
Roots of equation are
Solve each of the following quadratic equations:
√3x2 + 11x + 6√3 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = √(3;) b = 11; c = 6√3
= √3.6√3 = 3.6 = 18
(using 3 = √3.√3
And either of their sum or difference = b
= 11
Thus the two terms are 9 and 2
Sum = 9 + 2 = 11
Product = 9.2 = 18
√3 x(x + 3√3) + 2(x + 3√3) = 0
(using 9 = 3.3 = 3√3 √3)
(√3 x + 2)(x + 3√3) = 0
(√3 x + 2)(x + 3√3) = 0
Roots of equation are
Solve each of the following quadratic equations:
3√7x2 + 4x – √7 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 3√7 ;b = 4 ;c = -√7
= 3√7.-√7 = 3.-7 = -21
(using 7 = √7.√7)
And either of their sum or difference = b
= 4
Thus the two terms are 7 and - 3
Difference = 7 - 3 = 4
Product = 7× - 3 = - 21
( using 7 = √7.√7)
(√7 x-1)(3x + √7) = 0
(√7 x-1) = 0 or (3x + √7) = 0
x = 1/√7 or x = (-7)/√3
Roots of equation are
Solve each of the following quadratic equations:
√7x2 – 6x – 13√7 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
= √7.-13√7 = -13.7 = -91
And either of their sum or difference = b
= - 6
Thus the two terms are 7 and - 13
Difference = - 13 + 7 = - 6
Product = 7. - 13 = - 91
x(√7 x-13) + √7 (√7 x-13) = 0
(x + √7)(√7 x-13) = 0
(x + √7) = 0 or (√7 x-13) = 0
x = -√7 or x = 13/√7
Roots of equation are
Solve each of the following quadratic equations:
4√6x2 – 13 x – 2√6 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 4√6 ;b = -13 ;c = -2√6
= 4√6.-2√6 = -48
And either of their sum or difference = b
= - 13
Thus the two terms are - 16 and 3
Difference = - 16 + 3 = - 13
Product = - 16.3 = - 48
(On using √6 = √3 √2 and 16 = 4.2.√2 √2 )
⇒ (4√2 x + √3)(√3 x-2√2) = 0
⇒ (4√2 x + √3) = 0 or (√3 x-2√2) = 0
x = (-√3)/(4√2 ) or x = (2√2)/√3
Roots of equation are
Solve each of the following quadratic equations:
3x2 – 2√6x + 2 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 3; b = -2√(6;) c = 2
= 3.2 = 6
And either of their sum or difference = b
= -2√6
Thus the two terms are -√6 and -√6
Sum = -√6 -√6 = -2√6
Product = -√6. -√6 = -6 6 = √6. √6
(On using 3 = √3.√3 and √6 = √3 √2)
Equation has repeated roots
Solve each of the following quadratic equations:
√3x2 – 2√2x – 2√3 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = √3 b = -2√2 c = -2√3
= √3.-2√3 = -2.3 = -6
And either of their sum or difference = b
= -2√2
Thus the two terms are -3√2 and √2
Difference = -3√2 + √2 = -2√2
Product = -3√2 × √2 = -3.2 = -6
(On using3√2 = √3 √3 √2 = √3.√6)
(∵2√3 = √2 √2 √3 = √2.√6)
Roots of equation are
Solve each of the following quadratic equations:
x2 – 3√5x + 10 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 ;b = -3√5 ;c = 10
= 1.10 = 10
And either of their sum or difference = b
= -3√5
Thus the two terms are -2√5 and -√5
Sum = -2√5-√5 = -3√5
Product = -2√5. -√5 = 2.5 = 10 using 5 = √5. √5
(On using: 10 = 2.5 = 2.√5 √5)
x(x-2√5)-√5 (x-2√5) = 0
(x-√5)(x-2√5) = 0
(x-√5) = 0 or (x-2√5) = 0
x = √5 or x = 2√5
Hence the roots of equation are √5 or 2√5
Solve each of the following quadratic equations:
x2 – (√3 + 1) x + √3 = 0
On taking x common from first two terms and - 1 from last two
x(x-√3)-1(x-√3) = 0
(x-√3)(x-1) = 0
(x-√3) = 0 or (x-1) = 0
x = √3 or x = 1
Roots of equation are √3 or 1
Solve each of the following quadratic equations:
x2 + 3√3x – 30 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1; b = 3√3 ;c = -30
= 1. - 30 = - 30
And either of their sum or difference = b
= 3√3
Thus, the two terms are
Difference =
Product =
Hence the roots of equation are
Solve each of the following quadratic equations:
√2x2 + 7x + 5√2 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
=
And either of their sum or difference = b
= 7
Thus the two terms are 5 and 2
Sum = 5 + 2 = 7
Product = 5.2 = 10
Hence the roots of equation are
Solve each of the following quadratic equations:
5x2 + 13x + 8 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 5; b = 13; c = 8
= 5.8 = 40
And either of their sum or difference = b
= 13
Thus the two terms are 5 and 8
Sum = 5 + 8 = 13
Product = 5.8 = 40
Hence the roots of equation are
Solve each of the following quadratic equations:
x2 – (1+ √2)x + √2 = 0
On taking x common from first two terms and - 1 from last two
Hence the roots of equation are
Solve each of the following quadratic equations:
9x2 + 6x + 1 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 9; b = 6; c = 1
= 9.1 = 9
And either of their sum or difference = b
= 6
Thus the two terms are 3 and 3
Sum = 3 + 3 = 6
Product = 3.3 = 9
Hence the equation has repeated roots
Solve each of the following quadratic equations:
100x2 - 20x + 1 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 100 ;b = - 20 ;c = 1
= 100.1 = 100
And either of their sum or difference = b
= - 20
Thus the two terms are - 10 and - 10
Sum = - 10 - 10 = - 20
Product = - 10. - 10 = 100
10x(10x-1)-1(10x-1) = 0
(10x-1)(10x-1) = 0
(10x-1) = 0 or (10x-1) = 0
Roots of equation are repeated
Solve each of the following quadratic equations:
(taking LCM)
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 16; b = - 8 ;c = 1
= 16.1 = 16
And either of their sum or difference = b
= - 8
Thus the two terms are - 4 and - 4
Sum = - 4 - 4 = - 8
Product = - 4. - 4 = 16
4x(4x-1)-1(4x-1) = 0
(4x-1)(4x-1) = 0
(4x-1) = 0 or (4x-1) = 0
The equation has repeated roots
Solve each of the following quadratic equations:
taking LCM
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 10 ;b = - 3; c = - 1
= 10. - 1 = - 10
And either of their sum or difference = b
= - 3
Thus the two terms are - 5 and 2
Difference = - 5 + 2 = - 3
Product = - 5.2 = - 10
5x(2x-1) + 1(2x-1) = 0
(5x + 1)(2x-1) = 0
(5x + 1) = 0 or (2x-1) = 0
Solve each of the following quadratic equations:
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 2; b = - 5; c = 2
= 2.2 = 4
And either of their sum or difference = b
= - 5
Thus the two terms are - 4 and - 1
Difference = - 4 - 1 = - 5
Product = - 4. - 1 = 4
2x(x-2)-1(x-2) = 0
(2x-1)(x-2) = 0
(2x-1) = 0 or (x-2) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
2x2 + ax - a2 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 2; b = a; c = - a2
= - 2.a2 = - 2 a2
And either of their sum or difference = b
= a
Thus the two terms are 2a and - a
Difference = 2a - a = a
Product = 2a. - a = - 2a2
2x (x + a)-a (x + a) = 0
(2x-a) (x + a) = 0
(2x-a) = 0 or (x + a) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
4x2 + 4bx - (a2 - b2) = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 4 b = 4b c = - (a2 - b2)
= 4. - (a2 - b2)
= - 4a2 + 4b2
And either of their sum or difference = b
= 4b
Thus the two terms are 2(a + b) and - 2(a - b)
Difference = 2a + 2b - 2a + 2b = 4b
Product = 2(a + b). - 2(a - b) = - 4(a2 - b2)
using
⇒ 2x[2x + (a + b)]-(a-b) [2x + (a + b)] = 0
⇒ [2x + (a + b)] [2x-(a-b)] = 0
⇒ [2x + (a + b)] = 0 or [2x-(a-b)] = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
4x2 - 4a2x + (a4 - b4) = 0
4x2 - 4a2x + (a4 - b4) = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 4 ;b = - 4a2 ; c = (a4 - b4)
= 4. (a4 - b4)
= 4a4 - 4b4
And either of their sum or difference = b
= - 4a2
Thus the two terms are - 2(a2 + b2) and - 2(a2 - b2)
Difference = - 2(a2 + b2) - 2(a2 - b2)
= - 2a2 - 2b2 - 2a2 + 2b2
= - 4a2
Product = - 2(a2 + b2). - 2(a2 - b2)
= 4(a2 + b2)(a2 - b2)
= 4. (a4 - b4)
(∵ using a2 - b2 = (a + b) (a - b))
⇒ 4x2 - 4a2x + (a4 - b4) = 0
⇒ 4x2 - 4a2x + ((a2)2 – (b2)2) = 0
(∵ using a2 - b2 = (a + b) (a - b))
⇒ 4x2 - 2(a2 + b2) x - 2(a2 - b2) x + (a2 + b2) (a2 - b2) = 0
⇒ 2x [2x - (a2 + b2)] - (a2 - b2) [2x - (a2 + b2)] = 0
⇒ [2x - (a2 + b2)] [2x - (a2 - b2)] = 0
⇒ [2x - (a2 + b2)] = 0 or [2x - (a2 - b2)] = 0
Hence the roots of given equation are
Solve each of the following quadratic equations:
x2 + 5x - (a2 + a - 6) = 0
x2 + 5x - (a2 + a - 6) = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1; b = 5; c = - (a2 + a - 6)
= 1. - (a2 + a - 6)
= - (a2 + a - 6)
And either of their sum or difference = b
= 5
Thus the two terms are (a + 3) and - (a - 2)
Difference = a + 3 –a + 2
= 5
Product = (a + 3). - (a - 2)
= - [(a + 3)(a - 2)]
= - (a2 + a - 6)
x2 + 5x - (a2 + a - 6) = 0
⇒ x 2 + (a + 3)x - (a - 2)x - (a + 3)(a - 2) = 0
⇒ x[x + (a + 3)] - (a - 2) [x + (a + 3)] = 0
⇒ [x + (a + 3)] [x - (a - 2)] = 0
⇒ [x + (a + 3)] = 0 or [x - (a - 2)] = 0
⇒ x = - (a + 3) or x = (a - 2)
Hence the roots of given equation are - (a + 3) or (a - 2)
Solve each of the following quadratic equations:
x2 - 2ax - (4b2 - a2) = 0
x2 - 2ax - (4b2 - a2) = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = - 2a c = - (4b2 - a2)
= 1. - (4b2 - a2)
= - (4b2 - a2)
And either of their sum or difference = b
= - 2a
Thus the two terms are (2b - a) and - (2b + a)
Difference = 2b - a - 2b - a
= - 2a
Product = (2b - a) - (2b + a)
(∵ using a2 - b2 = (a + b) (a - b))
= - (4b2 - a2)
x2 - 2ax - (4b2 - a2) = 0
⇒ x2 + (2b - a)x - (2b + a)x - (2b - a)(2b + a) = 0
⇒ x[x + (2b - a)] - (2b + a)[x + (2b - a)] = 0
⇒ [x + (2b - a)] [x - (2b + a)] = 0
⇒ [x + (2b - a)] = 0 or [x - (2b + a)] = 0
⇒ x = (a - 2b) or x = (a + 2b)
Hence the roots of given equation are (a - 2b) or x = (a + 2b)
Solve each of the following quadratic equations:
x2 - (2b - 1)x + (b2 - b - 20) = 0
x2 - (2b - 1)x + (b2 - b - 20) = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1; b = - (2b - 1); c = b2 - b - 20
= 1(b2 - b - 20)
= (b2 - b - 20)
And either of their sum or difference = b
= - (2b - 1)
Thus the two terms are - (b - 5) and - (b + 4)
Sum = - (b - 5) - (b + 4)
= - b + 5 - b - 4
= - 2b + 1
= - (2b - 1)
Product = - (b - 5) - (b + 4)
= (b - 5) (b + 4)
= b2 - b - 20
x2 - (2b - 1)x + (b2 - b - 20) = 0
⇒ x2 - (b - 5)x - (b + 4)x + (b - 5)(b + 4) = 0
⇒ x[x - (b - 5)] - (b + 4)[x - (b - 5)] = 0
⇒ [x - (b - 5)] [x - (b + 4)] = 0
⇒ [x - (b - 5)] = 0 or [x - (b + 4)] = 0
⇒ x = (b - 5) or x = (b + 4)
Hence the roots of equation are (b - 5) or (b + 4)
Solve each of the following quadratic equations:
x2 + 6x - (a2 + 2a - 8) = 0
x2 + 6x - (a2 + 2a - 8) = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1; b = 6 ;c = - (a2 + 2a - 8)
= 1. - (a2 + 2a - 8)
= - (a2 + 2a - 8)
And either of their sum or difference = b
= 6
Thus the two terms are (a + 4) and - (a - 2)
Difference = a + 4 - a + 2
= 6
Product = (a + 4) - (a - 2)
= - (a2 + 2a - 8)
⇒ x2 + 6x - (a2 + 2a - 8) = 0
⇒ x2 + (a + 4)x - (a - 2)x - (a + 4)(a - 2) = 0
⇒ x [x + (a + 4)] - (a - 2) [x + (a + 4)] = 0
⇒ [x + (a + 4)] [x - (a - 2)] = 0
⇒ [x + (a + 4)] = 0 or [x - (a - 2)] = 0
x = - (a + 4) or x = (a - 2)
Hence the roots of equation are - (a + 4) or (a - 2)
Solve each of the following quadratic equations:
abx2 + (b2 - ac)x - bc = 0
abx2 + (b2 - ac)x - bc = 0
abx2 + (b2 - ac)x - bc = 0
abx2 + b2x - acx - bc = 0
bx (ax + b) - c (ax + b) = 0 taking bx common from first two terms and –c from last two
(ax + b) (bx - c) = 0
(ax + b) = 0 or (bx - c) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
x2 - 4ax - b2 + 4a2 = 0
x2 - 4ax - b2 + 4a2 = 0
x2 - 4ax – ((b)2 – (2a)2) = 0
{using a2 - b2 = (a + b)(a - b)}
x2 - (b + 2a)x + (b - 2a)x - (b + 2a)(b - 2a) = 0
⇒ x [x - (b + 2a)] + (b - 2a) [x - (b + 2a)] = 0
⇒ [x - (b + 2a)] [x + (b - 2a)] = 0
⇒ [x - (b + 2a)] = 0 or [x + (b - 2a)] = 0
⇒ x = (b + 2a) or x = - (b - 2a)
⇒ x = (2a + b) or x = (2a - b)
Hence the roots of equation are (2a + b) or (2a - b)
Solve each of the following quadratic equations:
4x2 - 2 (a2 + b2) x + a2b2 = 0
4x2 - 2a2x - 2 b2x + a2b2 = 0
2x (2x - a2) - b2(2x - a2) = 0
(On taking 2x common from first two terms and –b2 from last two)
⇒ (2x - a2) (2x - b2) = 0
⇒ (2x - a2) = 0 or (2x - b2) = 0
⇒
Hence the roots of equation are
Solve each of the following quadratic equations:
12abx2 - (9a2 - 8b2)x - 6ab = 0
12abx2 - (9a2 - 8b2)x - 6ab = 0
12abx2 - 9a2 x + 8b2x - 6ab = 0
3ax(4bx - 3a) + 2b(4bx - 3a) = 0 taking 3ax common from first two terms and 2b from last two
(4bx - 3a) (3ax + 2b) = 0
(4bx - 3a) = 0 or (3ax + 2b) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
a2b2x2 + b2x - a2x - 1 = 0
a2b2x2 + b2x - a2x - 1 = 0
b2x(a2x + 1) - 1(a2x + 1) = 0 taking b2x common from first two terms and - 1 from last two
(a2x + 1) (b2x - 1) = 0
(a2x + 1) = 0 or (b2x - 1) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
9x2 - 9 (a + b)x + (2 a2 + 5ab + 2b2) = 0
9x2 - 9(a + b)x + (2 a2 + 5ab + 2b2) = 0
Using the splitting middle term - the middle term of the general equation Ax2 + Bx + C is divided in two such values that:
Product = AC
For the given equation A = 9, B = - 9(a + b), C = 2a2 + 5ab + 2b2
= 9(2a2 + 5ab + 2b2)
= 9(2a2 + 4ab + ab + 2b2)
= 9[2a(a + 2b) + b(a + 2b)]
= 9(a + 2b)(2a + b)
= 3(a + 2b)3(2a + b)
Also,
3(a + 2b) + 3(2a + b) = 9(a + b)
Therefore,
9x2 - 9 (a + b) x + (2 a2 + 5ab + 2b2) = 0
9x2 - 3(2a + b)x - 3(a + 2b)x + (a + 2b) (2a + b) = 0
3x[3x - (2a + b)] - (a + 2b)[3x - (2a + b)] = 0
[3x - (2a + b)] [3x - (a + 2b)] = 0
[3x - (a + 2b)] = 0 or [3x - (2a + b)] = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
taking LCM
x2 + x = x + 16 cross multiplying
x2 - 16 = 0
x2 - (4)2 = 0 using a2 - b2 = (a + b)(a - b)
(x + 4) (x - 4) = 0
(x + 4) = 0 or (x - 4) = 0
x = 4 or x = - 4
Hence the roots of equation are 4, - 4.
Solve each of the following quadratic equations:
taking LCM
x + 4 = 2x2 + 3x cross multiplying
2x2 + 2x - 4 = 0 taking 2 common
x2 + x - 2 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 1 c = - 2
= 1. - 2 = - 2
And either of their sum or difference = b
= 1
Thus the two terms are 2 and - 1
Difference = 2 - 1 = 1
Product = 2. - 1 = - 2
x2 + x - 2 = 0
x2 + 2x - x - 2 = 0
x(x + 2) - (x + 2) = 0
(x + 2) (x - 1) = 0
(x + 2) = 0 or (x - 1) = 0
x = - 2 or x = 1
Hence the roots of equation are - 2 or 1.
Solve each of the following quadratic equations:
taking LCM
3x2 + 2x - 1 = 14x - 10 cross multiplying
3x2 - 12x + 9 = 0 taking 3 common
x2 - 4x + 3 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = - 4 c = 3
= 1.3 = 3
And either of their sum or difference = b
= - 4
Thus the two terms are - 3 and - 1
Sum = - 3 - 1 = - 4
Product = - 3. - 1 = 3
x2 - 4x + 3 = 0
x2 - 3x - x + 3 = 0
x(x - 3) - 1(x - 3) = 0
(x - 3) (x - 1) = 0
(x - 3) = 0 or (x - 1) = 0
x = 3 or x = 1
Hence the roots of equation are 3 or1.
Solve each of the following quadratic equations:
taking LCM
x2 + 4x - 5 = 7 cross multiplying
x2 + 4x - 12 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 4 c = - 12
= 1. - 12 = - 12
And either of their sum or difference = b
= 4
Thus the two terms are 6 and - 2
Difference = 6 - 2 = 4
Product = 6. - 2 = - 12
x2 + 4x - 12 = 0
x2 + 6x - 2x - 12 = 0
x(x + 6) - 2(x + 6) = 0
(x + 6)(x - 2) = 0
(x + 6) = 0 or (x - 2) = 0
x = - 6 or x = 2
Hence the roots of equation are - 6 or 2.
Solve each of the following quadratic equations:
taking LCM
4x2 + 4ax + 2bx = - 2ab cross multiplying
4x2 + 4ax + 2bx + 2ab = 0
4x(x + a) + 2b(x + a) = 0 taking 4x common from first two terms and 2b from last two
(x + a) (4x + 2b) = 0
(x + a) = 0 or (4x + 2b) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
taking LCM
8x2 + 8 = 17x2 - 34x cross multiplying
- 9x2 + 34x + 8 = 0
9x2 - 34x - 8 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 9 b = - 34 c = - 8
= 9. - 8 = - 72
And either of their sum or difference = b
= - 34
Thus the two terms are - 36 and 2
Difference = - 36 + 2 = - 34
Product = - 36.2 = - 72
9x2 - 34x - 8 = 0
9x2 - 36x + 2x - 8 = 0
9x(x - 4) + 2 (x - 4) = 0
(9x + 2)(x - 4) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
Given:
taking LCM
using (a - b)2 = a2 + b2 - 2ab
cross multiplying
18x2 - 48x + 130 = 105x - 140
18x2 - 153x + 270 = 0 taking 9 common
2x2 - 17x + 30 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 2 b = - 17 c = 30
= 2.30 = 60
And either of their sum or difference = b
= - 17
Thus the two terms are - 12 and - 5
Sum = - 12 - 5 = - 17
Product = - 12. - 5 = 60
2x2 - 17x + 30 = 0
2x2 - 12x - 5x + 30 = 0
2x(x - 6) - 5(x - 6) = 0
(x - 6) (2x - 5) = 0
(x - 6) = 0 or (2x - 5) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
Given:
taking LCM
using (a - b)2 = a2 + b2 - 2ab
8x2 - 8x + 4 = 17x2 - 17x cross multiplying
9x2 - 9x - 4 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 9 b = - 9 c = - 4
= 9. - 4 = - 36
And either of their sum or difference = b
= - 9
Thus the two terms are - 12 and 3
Sum = - 12 + 3 = - 9
Product = - 12.3 = - 36
9x2 - 9x - 4 = 0
9x2 - 12x + 3x - 4 = 0
3x(3x - 4) + 1(3x - 4) = 0
(3x - 4) (3x + 1) = 0
(3x - 4) = 0 or (3x + 1) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
Given: taking LCM
30x2 + 30x + 15 = 34x2 + 34x cross multiplying
4x2 + 4x - 15 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 4 b = 4 c = - 15
= 4. - 15 = - 60
And either of their sum or difference = b
= 4
Thus the two terms are 10 and - 6
Difference = 10 - 6 = 4
Product = 10. - 6 = - 60
4x2 + 4x - 15 = 0
4x2 + 10x - 6x - 15 = 0
2x(2x + 5) - 3(2x + 5) = 0
(2x + 5) (2x - 3) = 0
(2x + 5) = 0 or (2x - 3) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
Given:
taking LCM
3x2 - 33x + 87 = 5x2 - 60x + 175 cross multiplying
2x2 - 27x + 88 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 2 b = - 27 c = 88
= 2.88 = 176
And either of their sum or difference = b
= - 27
Thus the two terms are - 16 and - 11
Sum = - 16 - 11 = - 27
Product = - 16. - 11 = 176
2x2 - 27x + 88 = 0
2x2 - 16x - 11x + 88 = 0
2x(x - 8) - 11(x - 8) = 0
(x - 8) (2x - 11) = 0
(x - 8) = 0 or (2x - 11) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
Given:
taking LCM
cross multiplying
3x2 - 15x + 15 = 5x2 - 30x + 40
2x2 - 15x + 25 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 2 b = - 15 c = 25
= 2.25 = 50
And either of their sum or difference = b
= - 15
Thus the two terms are - 10 and - 5
Sum = - 10 - 5 = - 15
Product = - 10. - 5 = 50
2x2 - 15x + 25 = 0
2x2 - 10x - 5x + 25 = 0
2x(x - 5) - 5(x - 5) = 0
(x - 5)(2x - 5) = 0
(x - 5) = 0 or (2x - 5) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
Given:
taking LCM
cross multiplying
3x2 - 5x = 6x2 - 18x + 12
3x2 - 13x + 12 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 3 b = - 13 c = 12
= 3.12 = 36
And either of their sum or difference = b
= - 13
Thus the two terms are - 9 and - 4
Sum = - 9 - 4 = - 13
Product = - 9. - 4 = 36
3x2 - 13x + 12 = 0
3 x2 - 9x - 4x + 12 = 0
3x (x - 3) - 4(x - 3) = 0
(x - 3) (3x - 4) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
Given:
taking LCM
(3x + 4)(x + 4) = 5x2 + 15x + 10 cross multiplying
3x2 + 16x + 16 = 5x2 + 15x + 10
2x2 - x - 6 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 2 b = - 1 c = - 6
= 2. - 6 = - 12
And either of their sum or difference = b
= - 1
Thus the two terms are - 4 and 3
Difference = - 4 + 3 = - 1
Product = - 4.3 = 12
2x2 - x - 6 = 0
2x2 - 4x + 3x - 6 = 0
2x(x - 2) + 3(x - 2) = 0
(x - 2) (2x + 3) = 0
(x - 2) = 0 or (2x + 3) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
Given:
taking LCM
using (a + b)2 = a2 + b2 + 2ab; (a - b)2 = a2 + b2 - 2ab
19x2 - 42x - 15 = 30x2 + 35x - 15 cross multiplying
11 x2 + 77x = 0
11x(x + 7) = 0 taking 11x common
11x = 0 or (x + 7) = 0
x = 0 or x = - 7
Hence the roots of equation are 0, - 7
Solve each of the following quadratic equations:
Given:
taking LCM; using (a + b)2 = a2 + b2 + 2ab
47x2 + 162x - 33 = 385x2 - 176x - 33 cross multiplying
338x2 - 338x = 0
338x(x - 1) = 0 taking 338x common
338x = 0 or (x - 1) = 0
x = 1 or x = 0
Hence the roots of equation are 1, 0
Solve each of the following quadratic equations:
Given:
taking LCM; using (a + b)2 = a2 + b2 + 2ab
- 24x2 - 64x - 1 = 3(8x2 - 2x - 3) cross multiplying
- 24x2 - 64x - 1 = 24x2 - 6x - 9
48 x2 + 58x - 8 = 0 taking 2 common
24 x2 + 29x - 4 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 24 b = 29 c = - 4
= 24. - 4 = - 96
And either of their sum or difference = b
= 29
Thus the two terms are 32 and - 3
Difference = 32 - 3 = 29
Product = 32. - 3 = - 96
24 x2 + 29x - 4 = 0
24 x2 + 32x - 3x - 4 = 0
8x(3x + 4) - 1(3x + 4) = 0
(3x + 4)(8x - 1) = 0
(3x + 4) = 0 or (8x - 1) = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
Given: - - - - - - - - (1)
Let
y2 - 5y + 6 = 0 substituting value for y in (1)
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = - 5 c = 6
= 1.6 = 6
And either of their sum or difference = b
= - 5
Thus the two terms are - 3 and - 2
Difference = - 3 - 2 = - 5
Product = - 3. - 2 = 6
y2 - 5y + 6 = 0
y2 - 3y - 2y + 6 = 0
y(y - 3) - 2 (y - 3) = 0
(y - 3)(y - 2) = 0
(y - 3) = 0 or (y - 2) = 0
y = 3 or y = 2
Case I: if y = 3
x = 3x + 3
2x + 3 = 0
x = - 3/2
Case II: if y = 2
x = 2x + 2
x = - 2
Hence the roots of equation are
Solve each of the following quadratic equations:
Given:
taking - 1 with both terms
taking LCM
taking common (a - x - b)
taking LCM
(a - x + b)[2x - (a + b)] = 0
(a - x + b) = 0 or [2x - (a + b)] = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
Given:
taking LCM
taking common (a + b - abx)
taking LCM
(a + b - abx)[(a + b)x - 2] = 0
(a + b - abx) = 0 or [(a + b)x - 2] = 0
Hence the roots of equation are
Solve each of the following quadratic equations:
3(x + 2) + 3 - x = 10
Given: 3(x + 2) + 3 - x = 10
- - - - - - - - (1)
Let 3x = y - - - - - - - - - - (2)
substituting for y in (1)
9y2 - 10y + 1 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 9 b = - 10 c = 1
= 9.1 = 9
And either of their sum or difference = b
= - 10
Thus the two terms are - 9 and - 1
Sum = - 9 - 1 = - 10
Product = - 9. - 1 = 9
9y2 - 9y - 1y + 1 = 0
9y(y - 1) - 1(y - 1) = 0
(y - 1) (9y - 1) = 0
(y - 1) = 0 or (9y - 1) = 0
y = 1 or y = 1/9
3x = 1 or 3x = 1/9
On putting value of y in equation (2)
3x = 30 or 3x = 3 - 2
x = 0 or x = - 2
Hence the roots of equation are 0, - 2
Solve each of the following quadratic equations:
4(x + 1) + 4(1 - x) = 10
Given: 4(x + 1) + 4(1 - x) = 10
- - - - - - - (1)
Let 4x = y - - - - - - - - - - (2)
substituting for y in (1)
4y2 - 10y + 4 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 4 b = - 10 c = 4
= 4.4 = 16
And either of their sum or difference = b
= - 10
Thus the two terms are - 8 and - 2
Sum = - 8 - 2 = - 10
Product = - 8. - 2 = 16
4y2 - 10y + 4 = 0
4y2 - 8y - 2y + 4 = 0
4y(y - 2) - 2(y - 2) = 0
(y - 2) (4y - 2) = 0
(y - 2) = 0 or (4y - 2) = 0
y = 2 or y = 1/2
substituting the value of y in (2)
4x = 2 or 4x = 2 - 1
22x = 21 or 22x = 2 - 1
2x = 1 or 2x = - 1
Hence the roots of equation are
Solve each of the following quadratic equations:
22x - 3.2(x + 2) + 32 = 0
Given: 22x - 3.2(x + 2) + 32 = 0
(2x)2 - 3.2x.22 + 32 = 0 - - - - (1)
Let 2x = y - - - - - - (2)
substituting for y in (1)
y2 - 12y + 32 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = - 12 c = 32
= 1.32 = 32
And either of their sum or difference = b
= - 12
Thus the two terms are - 8 and - 4
Sum = - 8 - 4 = - 12
Product = - 8. - 4 = 32
y2 - 8y - 4y + 32 = 0
y(y - 8) - 4(y - 8) = 0
(y - 8) (y - 4) = 0
(y - 8) = 0 or (y - 4) = 0
y = 8 or y = 4
2x = 8 or 2x = 4
substituting the value of y in (2)
2x = 23 or 2x = 22
x = 2 or x = 3
Hence the roots of equation are 2, 3
Solve each of the following equations by using the method of completing the square:
x2 - 6x + 3 = 0
Given: x2 - 6x + 3 = 0
x2 - 6x = - 3
x2 - 2.x.3 + 32 = - 3 + 32 (adding 32 on both sides)
(x - 3)2 = - 3 + 9 = 6 using a2 - 2ab + b2 = (a - b)2
(taking square root on both sides)
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
x2 - 4x + 1 = 0
Given: x2 - 4x + 1 = 0
x2 - 4x = - 1
x2 - 2.x.2 + 22 = - 1 + 22 (adding 22 on both sides)
(x - 2)2 = - 1 + 4 = 3 using a2 - 2ab + b2 = (a - b)2
(taking square root on both sides)
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
x2 + 8x - 2 = 0
Given: x2 + 8x - 2 = 0
x2 + 8x = 2
x2 + 2.x.4 + 42 = 2 + 42 (adding 42 on both sides)
(x + 4)2 = 2 + 16 = 18 using a2 + 2ab + b2 = (a + b)2
(taking square root on both sides)
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
Given:
(adding on both sides)
using a2 + 2ab + b2 = (a + b)2
Hence the equation has repeated roots
Solve each of the following equations by using the method of completing the square:
2x2 + 5x - 3 = 0
Given: 2x2 + 5x - 3 = 0
4x2 + 10x - 6 = 0 (multiplying both sides by 2)
4x2 + 10x = 6
(adding on both sides)
using a2 + 2ab + b2 = (a + b)2
(taking square root on both sides)
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
3x2 - x - 2 = 0
Given: 3x2 - x - 2 = 0
9x2 - 3x - 6 = 0 (multiplying both sides by 3)
9x2 - 3x = 6
(adding on both sides)
using a2 - 2ab + b2 = (a - b)2
(taking square root on both sides)
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
8x2 - 14x - 15 = 0
Given: 8x2 - 14x - 15 = 0
16x2 - 28x - 30 = 0 (multiplying both sides by 2)
16x2 - 28x = 30
(adding on both sides)
using a2 - 2ab + b2 = (a - b)2
(taking square root on both sides)
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
7x2 + 3x - 4 = 0
Given: 7x2 + 3x - 4 = 0
49x2 + 21x - 28 = 0 (multiplying both sides by 7)
(adding on both sides)
using a2 + 2ab + b2 = (a + b)2
(taking square root on both sides)
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
3x2 - 2x - 1 = 0
Given: 3x2 - 2x - 1 = 0
9x2 - 6x = 3 (multiplying both sides by 3)
(adding on both sides)
using a2 - 2ab + b2 = (a - b)2
(taking square root on both sides)
3x - 1 = 2 or 3x - 1 = - 2
3x = 3 or 3x = - 1
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
5x2 - 6x - 2 = 0
Given: 5x2 - 6x - 2 = 0
25x2 - 30x - 10 = 0 (multiplying both sides by 5)
25x2 - 30x = 10
(adding on both sides)
using a2 - 2ab + b2 = (a - b)2
(taking square root on both sides)
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
Given:
2x2 - 5x + 2 = 0
4x2 - 10x + 4 = 0
4x2 - 10x = - 4 (multiplying both sides by 2)
(adding on both sides)
using a2 - 2ab + b2 = (a - b)2
(taking square root on both sides)
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
4x2 + 4bx - (a2 - b2) = 0
4x2 + 4bx = (a2 - b2)
(adding on both sides)
using a2 + 2ab + b2 = (a + b)2
(taking square root on both sides)
2x + b = - a or 2x + b = a
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
Given :
(adding on both sides)
using a2 - 2ab + b2 = (a - b)2
taking square root on both sides
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
Given:
(multiplying both sides by )
[Adding on both sides]
using a2 - 2ab + b2 = (a - b)2
(taking square root on both sides)
Hence the roots of equation are
Solve each of the following equations by using the method of completing the square:
√3x2 + 10 x + 7√3 = 0
Given:
(multiplying both sides with )
[Adding 52on both sides]
using a2 + 2ab + b2 = (a + b)2
(taking square root on both sides)
Hence the roots of equation are
By using the method of completing the square, show that the equation 2x2 + x + 4 = 0 has no real roots.
2x2 + x + 4 = 0
4x2 + 2x + 8 = 0 (multiplying both sides by 2)
4x2 + 2x = - 8
[Adding on both sides]
using a2 + 2ab + b2 = (a + b)2
But cannot be negative for any real value of x
So there is no real value of x satisfying the given equation.
Hence the given equation has no real roots.
Find the discriminant of each of the following equations:
2x2 – 7x + 6 = 0
Given: 2x2 – 7x + 6 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 2, b = – 7, c = 6
Discriminant D = b2 – 4ac
= (– 7)2 – 4.2.6
= 49 – 48 = 1
Find the discriminant of each of the following equations:
3x2 – 2x + 8 = 0
Given: 3x2 – 2x + 8 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 3, b = – 2, c = 8
Discriminant D = b2 – 4ac
= (– 2)2 – 4.3.8
= 4 – 96 = – 92
Find the discriminant of each of the following equations:
2x2 – 5√x + 4 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
=
= 25.2 – 32
= 50 – 32 = 18
Find the discriminant of each of the following equations:
√3x2 + 2√2x – 2√3 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
=
= 8 + 24 = 32
Find the discriminant of each of the following equations:
(x – 1)(2x – 1) = 0
Given: (x – 1)(2x – 1) = 0
2x2 – 3x + 1 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = , b = , c = – 1
Discriminant D = b2 – 4ac
= (– 3)2 – 4.2.1
= 9 – 8 = 1
Find the discriminant of each of the following equations:
1 – x = 2x2
Given: 1 – x = 2x2
2x2 + x – 1 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = , b = 1, c = – 1
Discriminant D = b2 – 4ac
= (1)2 – 4.2. – 1
= 1 + 8 = 9
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
x2 – 4x – 1 = 0
Given: x2 – 4x – 1 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 1, b = – 4, c = – 1
Discriminant D = b2 – 4ac
= (– 4)2 – 4.1. – 1
= 16 + 4 = 20 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
x2 – 6x + 4 = 0
Given: x2 – 6x + 4 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 1, b = – 6, c = 4
Discriminant D = b2 – 4ac
= (6)2 – 4.1.4
= 36 – 16 = 20 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
2x2 + x – 4 = 0
Given: 2x2 + x – 4 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 2, b = 1, c = – 4
Discriminant D = b2 – 4ac
= (1)2 – 4.2. – 4
= 1 + 32 = 33 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
25x2 + 30x + 7 = 0
Given: 25x2 + 30x + 7 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 25, b = 30, c = 7
Discriminant D = b2 – 4ac
= (30)2 – 4.25.7
= 900 – 700 = 200 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
16x2 = 24x + 1
Given: 16x2 = 24x + 1
16x2 – 24x – 1 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 16, b = – 24, c = – 1
Discriminant D = b2 – 4ac
= (– 24)2 – 4.16. – 1
= 576 + 64 = 640 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
15x2 – 28 = x
Given: 15x2 – 28 = x
15x2 – x – 28 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 15, b = – 1, c = – 28
Discriminant D = b2 – 4ac
= (– 1)2 – 4.15. – 28
= 1 + 1680 = 1681 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
2x2 – 2√2x + 1 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
=
= 8 – 8 = 0
Hence the roots of equation are real.
Roots are given by
Hence these are the repeated roots of the equation
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
√2x2 + 7x + 5√2 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
= 49 – 40 = 9 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
√3x2 + 10x – 8√3 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
= 100 + 96 = 196 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
√3x2 – 2√2x –2√3 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
=
= 8 + 24 = 32 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
2x2 + 6√3x – 60 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
=
= 180 + 480 = 588 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
4√3x2 + 5x – 2√3 = 0
Given
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
=
= 25 + 96 = 121 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
3x2 –2√6x + 2 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
= 24 – 24 = 0
Hence the roots of equation are real and repeated.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
2√3x2 – 5x + √3 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
=
= 25 – 24 = 10
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
x2 + x + 2 = 0
Given: x2 + x + 2 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 1, b = 1, c = 2
Discriminant D = b2 – 4ac
= (1)2 – 4.1.2
= 1 – 8 = – 7 < 0
Hence the roots of equation do not exist
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
2x2 + ax – a2 = 0
Given: 2x2 + ax – a2 = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = 2, B = a, C = – a2
Discriminant D = B2 – 4AC
= (a)2 – 4.2. – a2
= a2 + 8 a2 = 9a2 ≥0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
x2 – (√3 + 1) x + √3 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
Using a2 – 2ab + b2 = (a – b)2
Thus the roots of given equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
2x2 + 5√3x + 6 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
=
= 75 – 48 = 27 >
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
3x2 – 2x + 2 = 0
Given: 3x2 – 2x + 2 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 3, b = – 2, c = 2
Discriminant D = b2 – 4ac
= (– 2)2 – 4.3.2
= 4 – 24 = – 20 < 0
Hence the roots of equation do not exist
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
Given:
taking LCM
cross multiplying
x2 + 1 = 3x
x2 – 3x + 1 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 1, b = – 3, c = 1
Discriminant D = b2 – 4ac
= (– 3)2 – 4.1.1
= 9 – 4 = 5 >
Hence the roots of equation are real.
√D = √5
Roots α and β are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
Given:
taking LCM
3x2 – 6x + 2 = 0 cross multiplying
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 3, b = – 6, c = 2
Discriminant D = b2 – 4ac
= (– 6)2 – 4.3.2
= 36 – 24 = 12 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
Given:
taking LCM
x2 – 3x – 1 = 0 cross multiplying
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 1, b = – 3, c = – 1
Discriminant D = b2 – 4ac
= (– 3)2 – 4.1. – 1
= 9 + 4 = 13 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
Given:
taking LCM m2x+ n2 = mn – 2mnx
On cross multiplying
m2x+ 2mnx + n2 – mn = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = m2, b = 2mn, c = n2 – mn
Discriminant D = b2 – 4ac
= (2mn)2 – 4.m2. (n2 – mn)
= 4m2n2 – 4m2n2 + 4m3n > 0
Hence the roots of equation are real.
Roots α and β are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
36x2 – 12ax + (a2 – b2) = 0
Given: 36x2 – 12ax + (a2 – b2) = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = 36, B = – 12a, C = a2 – b2
Discriminant D = B2 – 4AC
= (– 12a)2 – 4.36.(a2 – b2)
= 144a2 – 144a2 + 144 b2 = 144 b2 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
x2 – 2ax + (a2 – b2) = 0
Given: x2 – 2ax + (a2 – b2) = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = 1, B = – 2a, C = a2 – b2
Discriminant D = B2 – 4AC
= (– 2a)2 – 4.1.(a2 – b2)
= 4a2 – 4a2 + 4 b2 = 4 b2 > 0
Hence the roots of equation are real.
Roots are given by
x = (a + b) or x = (a – b)
Hence the roots of equation are (a + b) or (a – b)
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
x2 – 2ax – (4b2 – a2) = 0
Given: x2 – 2ax – (4b2 – a2) = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = 1, B = – 2a, C = – (4b2 – a2)
Discriminant D = B2 – 4AC
= (– 2a)2 – 4.1. – (4b2 – a2)
= 4a2 – 4a2 + 16 b2 = 16b2 > 0
Hence the roots of equation are real.
Roots are given by
x = (a + 2b) or x = (a – 2b)
Hence the roots of equation are (a + 2b) or (a – 2b)
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
x2 + 6x – (a2 + b2 – 8) = 0
Given: x2 + 6x – (a2 + b2 – 8) = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = 1, B = 6, C = – (a2 + b2 – 8)
Discriminant D = B2 – 4AC
= (6)2 – 4.1. – (a2 + b2 – 8)
= 36+ 4a2 + 8a – 32 = 4a2 + 8a + 4
= 4(a2 + 2a + 1)
= 4(a + 1)2 > 0 Using a2 + 2ab + b2 = (a + b)2
Hence the roots of equation are real.
= 2(a + 1)
Roots are given by
x = (a – 2) or x = – (4 + a)
Hence the roots of equation are (a – 2) or – (4 + a)
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
x2 + 5x – (a2 + a – 6) = 0
Given: x2 + 5x – (a2 + a – 6) = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = 1, B = 5, C = – (a2 + a – 6)
Discriminant D = B2 – 4AC
= (5)2 – 4.1. – (a2 + a – 6)
= 25+ 4a2 + 4a – 24 = 4a2 + 4a + 1
= (2a + 1)2 > 0 Using a2 + 2ab + b2 = (a + b)2
Hence the roots of equation are real.
= (2a + 1)
Roots are given by
x = (a – 2) or x = – (a + 3)
Hence the roots of equation are (a – 2) or x = – (a + 3)
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
x2 – 4ax – b2 + 4a2 = 0
Given: x2 – 4ax – b2 + 4a2 = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = 1, B = – 4a, C = – b2 + 4a2
Discriminant D = B2 – 4AC
= (– 4a)2– 4.1. (– b2 + 4a2)
= 16a2 + 4b2 – 16a2 = 4 b2 > 0
Hence the roots of equation are real.
Roots are given by
x = (2a – b) or x = (2a + b)
Hence the roots of equation are (2a – b) or (2a + b)
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
4 x2 – 4a2x + (a4 – b4) = 0
Given: 4x2 – 4a2x + (a4 – b4) = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = 4, B = – 4a2, C = (a4 – b4)
Discriminant D = B2 – 4AC
= (– 4a2)2 – 4.4. (a4 – b4)
= 16a4 + 16b4 – 16a4 = 16 b4 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
4 x2 + 4bx – (a2 – b2) = 0
Given: 4x2 + 4bx – (a2 – b2) = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = 4, B = 4b, C = – (a2 – b2)
Discriminant D = B2 – 4AC
= (4b)2 – 4.4. – (a2 – b2)
= 16b2 + 16a2 – 16b2 = 16 a2 > 0
Hence the roots of equation are real.
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
x2 – (2b – 1)x + (b2 – b – 20) = 0
Given: x2 – (2b – 1)x + (b2 – b – 20) = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = 1, B = – (2b – 1), C = (b2 – b – 20)
Discriminant D = B2 – 4AC
= [ – (2b – 1)2] – 4.1. (b2 – b – 20) Using a2 – 2ab + b2 = (a – b)2
= 4b2 – 4b + 1 – 4b2 + 4b + 80 = 81 > 0
Hence the roots of equation are real.
Roots are given by
x = (b + 4) or x = (b – 5)
Hence the roots of equation are (b + 4) or (b – 5)
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
3a2x2 + 8abx + 4b2 = 0, a ≠ 0
Given: 3a2x2 + 8abx + 4b2 = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = 3a2, B = 8ab, C = 4b2
Discriminant D = B2 – 4AC
= (8ab)2 – 4.3a2. 4b2
= 64 a2b2 – 48a2b2 = 16a2b2 > 0
Hence the roots of equation are real.
= 4ab
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
a2b2x2 – (4b4 – 3a4)x – 12a2b2 = 0, a ≠ 0 and b ≠ 0
Given: a2b2x2 – (4b4 – 3a4)x – 12a2b2 = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = a2b2, B = – (4b4 – 3a4), C = – 12a2b2
Discriminant D = B2 – 4AC
= [ – (4b4 – 3a4)]2 – 4a2b2. – 12a2b2
= 16b8 – 24a4b4 + 9a8 + 48 a4b4
= 16b8 + 24a4b4 + 9a8
= (4b4 + 3a4)2 > 0 Using a2 + 2ab + b2 = (a + b)2
Hence the roots of equation are real.
=
Roots are given by
Hence the roots of equation are
Find the roots of each of the following equations, if they exist, by applying the quadratic formula:
12abx2 – (9a2 – 8b2)x – 6ab = 0, where a ≠ 0 and b ≠ 0
Given: 12abx2 – (9a2 – 8b2)x – 6ab = 0
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = 12ab, B = – (9a2 – 8b2), C = – 6ab
Discriminant D = B2 – 4AC
= [ – (9a2 – 8b2)]2 – 4.12ab. – 6ab
= 81a4 – 144a2b2 + 64b4 + 288 a2b2
= 81a4 + 144a2b2 + 64b4
= (9a2 + 8b2)2 > 0 Using a2 + 2ab + b2 = (a + b)2
Hence the roots of equation are real.
= 9a2 + 8b2
Roots are given by
Hence the roots of equation are
Find the nature of the roots of the following quadratic equations:
2x2 – 8x + 5 = 0
Given: 2x2 – 8x + 5 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 2, b = – 8, c = 5
Discriminant D = b2 – 4ac
= (– 8)2 – 4.2.5
= 64 – 40 = 24 > 0
Hence the roots of equation are real and unequal.
Find the nature of the roots of the following quadratic equations:
3x2 –2√6x + 2 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
= 24 – 24 = 0
Hence the roots of equation are real and equal.
Find the nature of the roots of the following quadratic equations:
5x2 – 4x + 1 = 0
Given: 5x2 – 4x + 1 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 5, b = – 4, c = 1
Discriminant D = b2 – 4ac
= (– 4)2 – 4.5.1
= 16 – 20 = – 4 < 0
Hence the equation has no real roots.
Find the nature of the roots of the following quadratic equations:
5x (x – 2) + 6 = 0
Given: 5x (x – 2) + 6 = 0
5x2 – 10x + 6 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 5, b = – 10, c = 6
Discriminant D = b2 – 4ac
= (– 10)2 – 4.5.6
= 100 – 120 = – 20 < 0
Hence the equation has no real roots.
Find the nature of the roots of the following quadratic equations:
12x2 – 4√15x + 5 = 0
Given:
Comparing with standard quadratic equation ax2 + bx + c = 0
Discriminant D = b2 – 4ac
= 240 – 240 = 0
Hence the equation has real and equal roots.
Find the nature of the roots of the following quadratic equations:
x2 – x + 2 = 0
Given: x2 – x + 2 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 1, b = – 1, c = 2
Discriminant D = b2 – 4ac
= (– 1)2 – 4.1.2
= 1 – 8 = – 7 < 0
Hence the equation has no real roots.
If a and b are distinct real numbers, show that the quadratic equation 2 (a2 + b2)x2 + 2(a + b)x + 1 = 0 has no real roots.
Given: 2 (a2 + b2)x2 + 2(a + b)x + 1 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 2 (a2 + b2), b = 2(a + b), c = 1
Discriminant D = b2 – 4ac
= [2(a + b)]2 – 4. 2 (a2 + b2).1
= 4(a2 + b2 + 2ab) – 8 a2 – 8b2
= 4a2 + 4b2 + 8ab – 8a2 – 8b2
= – 4a2 – 4b2 + 8ab
= – 4(a2 + b2 – 2ab)
= – 4(a – b)2 < 0
Hence the equation has no real roots.
Show that the roots of the equation x2 + px – q2 = 0 are real for all real values of p and q.
Given equation x2 + px – q2 = 0
a = 1 b = p x = – q2
Discriminant D = b2 – 4ac
= (p)2 – 4.1. – q2
= (p2 + 4q2) > 0
Thus the roots of equation are real.
For what values of k are the roots of the quadratic equation 3x2 + 2kx + 27 = 0 real and equal?
Given: 3x2 + 2kx + 27 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 3 b = 2k c = 27
Given that the roots of equation are real and equal
Thus D = 0
Discriminant D = b2 – 4ac = 0
(2k)2 – 4.3.27 = 0
4k2 – 324 = 0
4k2 = 324
k2 = 81 taking square root on both sides
k = 9 or k = – 9
The values of k are 9, – 9 for which roots of the quadratic equation are real and equal.
For what value of k are the roots of the quadratic equation kx(x –2√5) + 10 = 0 real and equal?
Given equation is
Comparing with standard quadratic equation ax2 + bx + c = 0
Given that the roots of equation are real and equal
Thus D = 0
Discriminant D = b2 – 4ac = 0
20k2 – 40k = 0
20k(k – 2) = 0
20k = 0 or (k – 2) = 0
k = 0 or k = 2
The values of k are 0, 2 for which roots of the quadratic equation are real and equal.
For what values of p are the roots of the equation 4 x2 + px + 3 = 0 real and equal?
Given equation is 4 x2 + px + 3 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 4 b = p c = 3
Given that the roots of equation are real and equal
Thus D = 0
Discriminant D = b2 – 4ac = 0
(p)2 – 4.4.3 = 0
p2 = 48
The values of p are for which roots of the quadratic equation are real and equal.
Find the nonzero value of k for which the roots of the quadratic equation 9x2 – 3kx + k = 0 are real and equal.
Given equation is 9x2 – 3kx + k = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 9 b = – 3k c = k
Given that the roots of equation are real and equal
Thus D = 0
Discriminant D = b2 – 4ac = 0
(– 3k)2 – 4.9.k = 0
9 k2 – 36k = 0
9k(k – 4) = 0
9k = 0 or(k – 4) = 0
k = 0 or k = 4
But given k is non zero hence k = 4 for which roots of the quadratic equation are real and equal.
Find the values of k for which the quadratic equation (3k + 1) x2 + 2(k + 1)x + 1 = 0 has real and equal roots.
Given equation is (3k + 1) x2 + 2(k + 1)x + 1 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = (3k + 1) b = 2(k + 1) c = 1
Given that the roots of equation are real and equal
Thus D = 0
Discriminant D = b2 – 4ac = 0
(2k + 2)2 – 4.(3k + 1).1 = 0 using (a + b)2 = a2 + 2ab + b2
4k2 + 8k + 4 – 12k – 4 = 0
4k2 – 4k = 0
4k(k – 1) = 0
k = 0 (k – 1) = 0
k = 0 k = 1
The values of k are 0, 1 for which roots of the quadratic equation are real and equal.
Find the values of p for which the quadratic equation (2p + 1)x2 – (7p + 2)x + (7p – 3) = 0 has real and equal roots.
Given equation is (2p + 1)x2 – (7p + 2)x + (7p – 3) = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = (2p + 1) b = – (7p + 2) c = (7p – 3)
Given that the roots of equation are real and equal
Thus D = 0
Discriminant D = b2 – 4ac = 0
[ – (7p + 2)]2 – 4.(2p + 1).(7p – 3) = 0 using (a + b)2 = a2 + 2ab + b2
(49p2 + 28p + 4) – 4(14p2 + p – 3) = 0
49p2 + 28p + 4 – 56p2 – 4p + 12 = 0
– 7p2 + 24p + 16 = 0
7p2 – 24p – 16 = 0
7p2 – 28p + 4p – 16 = 0
7p(p – 4) + 4(p – 4) = 0
(7p + 4)(p – 4) = 0
(7p + 4) = 0 or (p – 4) = 0
The values of p are for which roots of the quadratic equation are real and equal.
Find the values of p for which the quadratic equation (p + 1)x2 – 6 (p + 1) x + 3 (p + 9) = 0, p 1 has equal roots. Hence, find the roots of the equation.
Given equation is (p + 1)x2 – 6 (p + 1) x + 3 (p + 9) = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = (p + 1) b = – 6(p + 1) c = 3(p + 9)
Given that the roots of equation are equal
Thus D = 0
Discriminant D = b2 – 4ac = 0
[ – 6(p + 1)]2 – 4.(p + 1).3(p + 9) = 0
36(p + 1)(p + 1) – 12(p + 1)(p + 9) = 0
12(p + 1)[3(p + 1) – (p + 9)] = 0
12(p + 1)[3p + 3 – p – 9] = 0
12(p + 1)[2p – 6] = 0
(p + 1) = 0 or [2p – 6] = 0
p = – 1 or p = 3
The values of p are – 1, 3 for which roots of the quadratic equation are real and equal.
If – 5 is a root of the quadratic equation 2x2 + px – 15 = 0 and the quadratic equation p (x2 + x) + k = 0 has equal roots, find the value of k.
Given that – 5 is a root of the quadratic equation 2x2 + px – 15 = 0
2(– 5)2 – 5p – 15 = 0
5p = 35
p = 7
Given equation is p (x2 + x) + k = 0
px2 + px + k = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = p b = p c = k
Given that the roots of equation are equal
Thus D = 0
Discriminant D = b2 – 4ac = 0
[p]2 – 4.p.k = 0
72 – 28k = 0
49 – 28k = 0
The value of k is for which roots of the quadratic equation are equal.
If 3 is a root of the quadratic equation x2 – x + k = 0, find the value of p so that the roots of the equation x2 + k (2x + k + 2) + p = 0 are equal.
Given 3 is a root of the quadratic equation x2 – x + k = 0
(3)2 – 3 + k = 0
k + 6 = 0
k = – 6
Given equation is x2 + k (2x + k + 2) + p = 0
x2 + 2kx + (k2 + 2k + p) = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 1 b = 2k c = k2 + 2k + p
Given that the roots of equation are equal
Thus D = 0
Discriminant D = b2 – 4ac = 0
(2k)2 – 4.1. (k2 + 2k + p) = 0
4k2 – 4k2 – 8k – 4p = 0
– 8k – 4p = 0
4p = – 8k
p = – 2k
p = – 2. – 6 = 12
p = 12
The value of p is – 12 for which roots of the quadratic equation are equal.
If – 4 is a root of the equation x2 + 2x + 4p = 0, find the value of k for which the quadratic equation x2 + px (1 + 3k) + 7(3 + 2k) = 0 has equal roots.
Given – 4 is a root of the equation x2 + 2x + 4p = 0
(– 4)2 + 2(– 4) + 4p = 0
8 + 4p = 0
p = – 2
The quadratic equation x2 + px (1 + 3k) + 7(3 + 2k) = 0 has equal roots
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 1 b = p(1 + 3k) c = 7(3 + 2k)
Thus D = 0
Discriminant D = b2 – 4ac = 0
[p(1 + 3k)]2 – 4.1.7(3 + 2k) = 0
[ – 2(1 + 3k)]2 – 4.1.7(3 + 2k) = 0
4(1 + 6k + 9k2) – 4.7(3 + 2k) = 0 using (a + b)2 = a2 + 2ab + b2
4(1 + 6k + 9k2 – 21 – 14k) = 0
9k2 – 8k – 20 = 0
9k2 – 18k – 10k – 20 = 0
9k(k – 2) + 10(k – 2) = 0
(9k + 10)(k – 2) = 0
The value of k is for which roots of the quadratic equation are equal.
If the quadratic equation (1 + m2)x2 + 2mcx + c2 – a2 = 0 has equal roots, prove that c2 = a2(1 + m2) .
The quadratic equation (1 + m2) x2 + 2mcx + c2 – a2 = 0 has equal roots
Comparing with standard quadratic equation ax2 + bx + c = 0
a = (1 + m2) b = 2mc c = c2 – a2
Thus D = 0
Discriminant D = b2 – 4ac = 0
(2mc)2 – 4.(1 + m2)(c2 – a2) = 0
4 m2c2 – 4c2 + 4a2 – 4 m2c2 + 4 m2a2 = 0
– 4c2 + 4a2 + 4m2a2 = 0
a2 + m2a2 = c2
c2 = a2 (1 + m2)
Hence proved
If the roots of the equation (c2 – ab)x2 – 2(a2 – bc)x + (b2 – ac) = 0 are real and equal, show that either a = 0 or (a3 + b3 + c3) = 3abc.
Given that the roots of the equation (c2 – ab)x2 – 2(a2 – bc)x + (b2 – ac) = 0 are real and equal
Comparing with standard quadratic equation ax2 + bx + c = 0
a = (c2 – ab) b = – 2(a2 – bc) c = (b2 – ac)
Thus D = 0
Discriminant D = b2 – 4ac = 0
[ – 2(a2 – bc)]2 – 4(c2 – ab) (b2 – ac) = 0
4(a4 – 2a2bc + b2c2) – 4(b2c2 – ac3 – ab3 + a2bc) = 0
using (a – b)2 = a2 – 2ab + b2
a4 – 2a2bc + b2c2 – b2c2 + ac3 + ab3 – a2bc = 0
a4 – 3a2bc + ac3 + ab3 = 0
a (a3 – 3abc + c3 + b3) = 0
a = 0 or (a3 – 3abc + c3 + b3) = 0
Hence proved a = 0 or a3 + c3 + b3 = 3abc
Find the values of p for which the quadratic equation 2x2 + px + 8 = 0 has real roots.
Given that the quadratic equation 2x2 + px + 8 = 0 has real roots
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 2 b = p c = 8
Thus D = 0
Discriminant D = b2 – 4ac≥0
(p)2 – 4.2.8≥0
(p)2 – 64≥0
p2 ≥ 64 taking square root on both sides
p≥8 or p≤ – 8
The roots of equation are real for p≥8 or p≤ – 8
Find the value of a for which the equation (a – 12)x2 + 2(a – 12)x + 2 = 0 has equal roots.
Given that the quadratic equation (a – 12)x2 + 2(a – 12)x + 2 = 0 has equal roots
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = (a – 12) B = 2(a – 12) C = 2
Thus D = 0
Discriminant D = B2 – 4AC≥0
[2(a – 12)]2 – 4(a – 12)2≥0
4(a2 + 144 – 24a) – 8a + 96 = 0 using (a – b)2 = a2 – 2ab + b2
4a2 + 576 – 96a – 8a + 96 = 0
4a2 – 104a + 672 = 0
a2 – 26a + 168 = 0
a2 – 14a – 12a + 168 = 0
a(a – 14) – 12(a – 14) = 0
(a – 14)(a – 12) = 0
a = 14 or a = 12
for a = 12 the equation will become non quadratic – – (a – 12)x2 + 2(a – 12)x + 2 = 0
A, B will become zero
Thus value of a = 14 for which the equation has equal roots.
Find the value of k for which the roots of 9x2 + 8kx + 16 = 0 are real and equal.
Given that the quadratic equation 9x2 + 8kx + 16 = 0 roots are real and equal.
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 9 b = 8k c = 16
Thus D = 0
Discriminant D = b2 – 4ac = 0
(8k)2 – 4.9.16 = 0
64k2 – 576 = 0
k2 = 9 taking square root both sides
Thus k = 3 or k = – 3 for which the roots are real and equal.
Find the values of k for which the given quadratic equation has real and distinct roots:
(i) Given: kx2 + 6x + 1 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = k b = 6 c = 1
For real and distinct roots: D > 0
Discriminant D = b2 – 4ac > 0
62 – 4k > 0
36 – 4k > 0
4k < 36
k < 9
(ii) Given: x2 – kx + 9 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 1 b = – k c = 9
For real and distinct roots: D > 0
Discriminant D = b2 – 4ac > 0
(– k)2 – 4.1.9 = k2 – 36 > 0
k2 > 36
k > 6or k < – 6 taking square root both sides
(iii) 9x2 + 3kx + 4 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 9 b = 3k c = 4
For real and distinct roots: D > 0
Discriminant D = b2 – 4ac > 0
(3k)2 – 4.4.9 = 9k2 – 144 > 0
9k2 > 144
k2 > 16
k > 4ork < – 4 taking square root both sides
(iv) 5x2 – kx + 1 = 0
Comparing with standard quadratic equation ax2 + bx + c = 0
a = 5 b = – k c = 1
For real and distinct roots: D > 0
Discriminant D = b2 – 4ac > 0
(– k)2 – 4.5.1 = k2 – 20 > 0
k2 > 20
k > 2√5 or k < –2√5 taking square root both sides
If a and b are real and ab then show that the roots of the equation (a – b)x2 + 5(a + b)x – 2(a – b) = 0 are real and unequal.
Comparing with standard quadratic equation ax2 + bx + c = 0
a = (a – b) b = 5(a + b) c = – 2(a – b)
Discriminant D = b2 – 4ac
= [5(a + b)]2 – 4(a – b)(– 2(a – b))
= 25(a + b)2 + 8(a – b)2
Since a and b are real and ab then (a + b)2 > 0 (a – b)2 > 0
8(a – b)2 > 0 – – – – (1) product of two positive numbers is always positive
25(a + b)2 > 0 – – – – (2) product of two positive numbers is always positive
Adding (1) and (2) we get
8(a – b)2 + 25(a + b)2 > 0 (sum of two positive numbers is always positive)
D > 0
Hence the roots of given equation are real and unequal.
If the roots of the equation (a2 + b2)x2 – 2 (ac + bd)x + (c2 + d2) = 0 are a c equal, prove that
Given the roots of the equation are equation (a2 + b2)x2 – 2 (ac + bd)x + (c2 + d2) = 0 are equal.
Comparing with standard quadratic equation ax2 + bx + c = 0
a = (a2 + b2) b = – 2(ac + bd) c = (c2 + d2)
For real and distinct roots: D = 0
Discriminant D = b2 – 4ac = 0
[ – 2(ac + bd)]2 – 4(a2 + b2)(c2 + d2) = 0
4(a2c2 + b2d2 + 2abcd) – 4(a2c2 + a2d2 + b2c2 + b2d2) = 0
using (a + b)2 = a2 + 2ab + b2
4(a2c2 + b2d2 + 2abcd – a2c2 – a2d2 – b2c2 – b2d2) = 0
2abcd – a2d2 – b2c2 = 0
– (2abcd + a2d2 + b2c2) = 0
(ad – bc)2 = 0
ad = bc
Hence proved.
If the roots of the equations ax2 + 2bx + c = 0 and are simultaneously real then prove that b2 = ac.
Given the roots of the equations ax2 + 2bx + c = 0 are real.
Comparing with standard quadratic equation Ax2 + Bx + C = 0
A = a B = 2b C = c
Discriminant D1 = B2 – 4AC ≥ 0
= (2b)2 – 4.a.c ≥ 0
= 4(b2 –ac) ≥ 0
= (b2 –ac) ≥ 0 – – – – – (1)
For the equation
Discriminant D2 = b2 – 4ac ≥ 0
=
= 4(ac – b2) ≥0
= – 4(b2–ac) ≥0
= (b2 –ac) ≥0 – – – – – (2)
The roots of the are simultaneously real if (1) and (2) are true together
b2 –ac = 0
b2 = ac
Hence proved.
The sum of a natural number and its square is 156. Find the number.
Let the required number be x
According to given condition,
x + x2 = 156
x2 + x – 156 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 1 c = – 156
= 1. – 156 = – 156
And either of their sum or difference = b
= 1
Thus the two terms are 13 and – 12
Sum = 13 – 12 = 1
Product = 13. – 12 = – 156
x2 + x – 156 = 0
x2 + 13x – 12x – 156 = 0
x(x + 13) – 12 (x + 13) = 0
(x – 12) (x + 13) = 0
x = 12 or x = – 13
x cannot be negative
Hence the required natural number is 12
The sum of a natural number and its positive square root is 132. Find the number.
Let the required number be x
According to given condition,
putting we get
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 1 c = – 132
= 1. – 132 = – 132
And either of their sum or difference = b
= 1
Thus the two terms are 12 and – 11
Difference = 12 – 11 = 1
Product = 12. – 11 = – 132
y(y + 12) – 11(y + 12) = 0
(y + 12) (y – 11) = 0
(y + 12) = 0 or (y – 11) = 0
y = – 12 or y = 11 but y cannot be negative
Thus y = 11
Now
x = y squaring both sides
x = (11)2 = 121
Hence the required number is 121
The sum of two natural numbers is 28 and their product is 192. Find the numbers.
Let the required number be x and 28 – x
According to given condition,
x(28 – x) = 192
x2 – 28x + 192 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 28 c = 192
= 1.192 = 192
And either of their sum or difference = b
= – 28
Thus the two terms are – 16 and – 12
Sum = – 16 – 12 = – 28
Product = – 16. – 12 = 192
x2 – 28x + 192 = 0
x2 – 16x – 12x + 192 = 0
x(x – 16) – 12(x – 16) = 0
(x – 16) (x – 12) = 0
(x – 16) = 0 or (x – 12) = 0
x = 16 or x = 12
Hence the required numbers are 16, 12
The sum of the squares of two consecutive positive integers is 365. Find the integers.
Let the required two consecutive positive integers be x and x + 1
According to given condition,
x2 + (x + 1)2 = 365
x2 + x2 + 2x + 1 = 365 using (a + b)2 = a2 + 2ab + b2
2x2 + 2x – 364 = 0
x2 + x – 182 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 1 c = – 182
= 1. – 182 = – 182
And either of their sum or difference = b
= 1
Thus the two terms are 14 and – 13
Difference = 14 – 13 = 1
Product = 14. – 13 = – 182
x2 + x – 182 = 0
x2 + 14x – 13x – 182 = 0
x(x + 14) – 13(x + 14) = 0
(x + 14) (x – 13) = 0
(x + 14) = 0 or (x – 13) = 0
x = – 14 or x = 13
x = 13 (x is a positive integer)
x + 1 = 13 + 1 = 14
Thus the required two consecutive positive integers are 13, 14
The sum of the squares of two consecutive positive odd numbers is 514. Find the numbers.
Let the two consecutive positive odd numbers be x and x + 2
According to given condition,
x2 + (x + 2)2 = 514
x2 + x2 + 4x + 4 = 514 using (a + b)2 = a2 + 2ab + b2
2x2 + 4x – 510 = 0
x2 + 2x – 255 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 2 c = – 255
= 1. – 255 = – 255
And either of their sum or difference = b
= 2
Thus the two terms are 17 and – 15
Difference = 17 – 15 = 2
Product = 17. – 15 = – 255
x2 + 2x – 255 = 0
x2 + 17x – 15x – 255 = 0
x(x + 17) – 15(x + 17) = 0
(x + 17) (x – 15) = 0
(x + 17) = 0 or (x – 15) = 0
x = – 17 or x = 15
x = 15 (x is positive odd number)
x + 2 = 15 + 2 = 17
Thus the two consecutive positive odd numbers are 15 and 17
The sum of the squares of two consecutive positive even numbers is 452. Find the numbers.
Let the two consecutive positive even numbers be x and (x + 2)
According to given condition,
x2 + (x + 2)2 = 452
x2 + x2 + 4x + 4 = 452 using (a + b)2 = a2 + 2ab + b2
2x2 + 4x – 448 = 0
x2 + 2x – 224 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 2 c = – 224
= 1. – 224 = – 224
And either of their sum or difference = b
= 2
Thus the two terms are 16 and – 14
Difference = 16 – 14 = 2
Product = 16. – 14 = – 224
x2 + 2x – 224 = 0
x2 + 16x – 14x – 224 = 0
x(x + 16) – 14(x + 16) = 0
(x + 16) (x – 14) = 0
(x + 16) = 0 or (x – 14) = 0
x = – 16 or x = 14
x = 14 (x is positive odd number)
x + 2 = 14 + 2 = 16
Thus the two consecutive positive even numbers are 14 and 16
The product of two consecutive positive integers is 306. Find the integers.
Let the two consecutive positive integers be x and (x + 1)
According to given condition,
x(x + 1) = 306
x2 + x – 306 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 1 c = – 306
= 1. – 306 = – 306
And either of their sum or difference = b
= 1
Thus the two terms are 18 and – 17
Difference = 18 – 17 = 1
Product = 18. – 17 = – 306
x2 + x – 306 = 0
x2 + 18x – 17x – 306 = 0
x(x + 18) – 17(x + 18) = 0
(x + 18) (x – 17) = 0
(x + 18) = 0 or (x – 17) = 0
x = – 18 or x = 17
but x = 17 ( x is a positive integers)
x + 1 = 17 + 1 = 18
Thus the two consecutive positive integers are 17 and 18
Two natural numbers differ by 3 and their product is 504. Find the numbers.
Let the two natural numbers be x and (x + 3)
According to given condition,
x(x + 3) = 504
x2 + 3x – 504 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 3 c = – 504
= 1. – 504 = – 504
And either of their sum or difference = b
= 3
Thus the two terms are 24 and – 21
Difference = 24 – 21 = 3
Product = 24. – 21 = – 504
x2 + 3x – 504 = 0
x2 + 24x – 21x – 504 = 0
x (x + 24) – 21(x + 24) = 0
(x + 24) (x – 21) = 0
(x + 24) = 0 or (x – 21) = 0
x = – 24 or x = 21
Case I: x = 21
x + 3 = 21 + 3 = 24
The numbers are (21, 24)
Case I: x = – 24
x + 3 = – 24 + 3 = – 21
The numbers are ( – 24, – 21)
Find two consecutive multiples of 3 whose product is 648.
Let the required consecutive multiples of 3 be 3x and 3(x + 1)
According to given condition,
3x.3(x + 1) = 648
9(x2 + x) = 648
x2 + x = 72
x2 + x – 72 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 1 c = – 72
= 1. – 72 = – 72
And either of their sum or difference = b
= 1
Thus the two terms are 9 and – 8
Difference = 9 – 8 = 1
Product = 9. – 8 = – 72
x2 + 9x – 8x – 72 = 0
x (x + 9) – 8(x + 9) = 0
(x + 9) (x – 8) = 0
(x + 9) = 0 or (x – 8) = 0
x = – 9 or x = 8
x = 8 (rejecting the negative values)
3x = 3.8 = 24
3(x + 1) = 3(8 + 9) = 3.9 = 27
Hence, the required numbers are 24 and 27
Find two consecutive positive odd integers whose product is 483.
Let the required consecutive positive odd integers be x and (x + 2)
According to given condition,
x (x + 2) = 483
x2 + 2x – 483 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 2 c = – 483
= 1. – 483 = – 483
And either of their sum or difference = b
= 2
Thus the two terms are 23 and – 21
Difference = 23 – 21 = 2
Product = 23. – 21 = – 483
x2 + 2x – 483 = 0
x2 + 23x – 21x – 483 = 0
x (x + 23) – 21(x + 23) = 0
(x + 23) (x – 21) = 0
(x + 23) = 0 or (x – 21) = 0
x = – 23 or x = 21
x = 21 (x is a positive odd integer)
x + 2 = 21 + 2 = 23
Hence, the required integers are 21 and 23
Find two consecutive positive even integers whose product is 288.
Let the two consecutive positive even integers be x and (x + 2)
According to given condition,
x (x + 2) = 288
x2 + 2x – 288 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 2 c = – 288
= 1. – 288 = – 288
And either of their sum or difference = b
= 2
Thus the two terms are 18 and – 16
Difference = 18 – 16 = 2
Product = 18. – 16 = – 288
x2 + 18x – 16x – 288 = 0
x (x + 18) – 16(x + 18) = 0
(x + 18) (x – 16) = 0
(x + 18) = 0 or (x – 16) = 0
x = – 18 or x = 16
x = 16 (x is a positive odd integer)
x + 2 = 16 + 2 = 18
Hence, the required integers are 16 and 18
The sum of two natural numbers is 9 and the sum of their reciprocals is 1/2. Find the numbers.
Let the required natural numbers x and (9 – x)
According to given condition,
taking LCM
cross multiplying
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 9 c = 18
= 1.18 = 18
And either of their sum or difference = b
= – 9
Thus the two terms are – 6 and – 3
Sum = – 6 – 3 = – 9
Product = – 6. – 3 = 18
x(x – 6) – 3(x – 6) = 0
(x – 6) (x – 3) = 0
(x – 6) = 0 or (x – 3) = 0
x = 6 or x = 3
Case I: when x = 6
9 – x = 9 – 6 = 3
Case II: when x = 3
9 – x = 9 – 3 = 6
Hence required numbers are 3 and 6.
The sum of two natural numbers is 15 and the sum of their reciprocals is 3/10. Find the numbers.
Let the required natural numbers x and (15 – x)
According to given condition,
taking LCM
cross multiplying
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 15 c = 50
= 1.50 = 50
And either of their sum or difference = b
= – 15
Thus the two terms are – 10 and – 5
Sum = – 10 – 5 = – 15
Product = – 10. – 5 = 50
x(x – 10) – 5(x – 10) = 0
(x – 5) (x – 10) = 0
(x – 5) = 0 or (x – 10) = 0
x = 5 or x = 10
Case I: when x = 5
15 – x = 15 – 5 = 10
Case II: when x = 10
15 – x = 15 – 10 = 5
Hence required numbers are 5 and 10.
The difference of two natural numbers is 3 and the difference of their 3 reciprocals is 3/28.Find the numbers.
Let the required natural numbers x and (x + 3)
x < x + 3
Thus
According to given condition,
taking LCM
cross multiplying
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 3 c = – 28
= 1. – 28 = – 28
And either of their sum or difference = b
= 3
Thus the two terms are 7 and – 4
Difference = 7 – 4 = 3
Product = 7. – 4 = – 28
x(x + 7) – 4(x + 7) = 0
(x – 4) (x + 7) = 0
(x – 4) = 0 or (x + 7) = 0
x = 4 or x = – 7
x = 4 (x < x + 3)
x + 3 = 4 + 3 = 7
Hence required numbers are 4 and 7.
The difference of two natural numbers is 5 and the difference of their reciprocals is 5/14. Find the numbers.
Let the required natural numbers x and (x + 5)
x < x + 5
Thus
According to given condition,
taking LCM
cross multiplying
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 5 c = – 14
= 1. – 14 = – 14
And either of their sum or difference = b
= 5
Thus the two terms are 7 and – 2
Difference = 7 – 2 = 5
Product = 7. – 2 = – 14
x (x + 7) – 2(x + 7) = 0
(x – 2) (x + 7) = 0
(x – 2) = 0 or (x + 7) = 0
x = 2 or x = – 7
x = 2 (x < x + 3)
x + 5 = 2 + 5 = 7
Hence required natural numbers are 2 and 7.
The sum of the squares of two consecutive multiples of 7 is 1225. Find the multiples.
Let the required consecutive multiples of 7 be 7x and 7(x + 1)
According to given condition,
(7x)2 + [7(x + 1)]2 = 1225
49 x2 + 49(x2 + 2x + 1) = 1225 using (a + b)2 = a2 + 2ab + b2
49 x2 + 49x2 + 98x + 49 = 1225
98x2 + 98x–1176 = 0
x2 + x – 12 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 1 c = – 12
= 1. – 12 = – 12
And either of their sum or difference = b
= 1
Thus the two terms are 4 and – 3
Difference = 4 – 3 = 1
Product = 4. – 3 = – 12
x2 + 4x – 3x – 12 = 0
x(x + 4) – 3(x + 4) = 0
(x – 3) (x + 4) = 0
(x – 3) = 0 or (x + 4) = 0
x = 3 or x = – 4
when x = 3,
7x = 7.3 = 21
7(x + 1) = 7(3 + 1) = 7.4 = 28
Hence required multiples are 21, 28.
The sum of a natural number and its reciprocal is 65/8. Find the number.
Let the required natural numbers x
According to given condition,
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 8 b = – 65 c = 8
= 8.8 = 64
And either of their sum or difference = b
= – 65
Thus the two terms are – 64 and – 1
Difference = – 64 – 1 = – 65
Product = – 64. – 1 = 64
8x (x – 8) – 1(x – 8) = 0
(x – 8) (8x – 1) = 0
(x – 8) = 0 or (8x – 1) = 0
x = 8 or x = 1/8
x = 8 (x is a natural number)
Hence the required number is 8.
Divide 57 into two parts whose product is 680.
Let the two consecutive positive even integers be x and (57 – x)
According to given condition,
x (57 – x) = 680
57x – x2 = 680
x2 – 57x – 680 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 57 c = – 680
= 1. – 680 = – 680
And either of their sum or difference = b
= – 57
Thus the two terms are – 40 and – 17
Sum = – 40 – 17 = – 57
Product = – 40. – 17 = – 680
x2 – 57x – 680 = 0
x2 – 40x – 17x – 680 = 0
x (x – 40) – 17(x – 40) = 0
(x – 40) (x – 17) = 0
(x – 40) = 0 or (x – 17) = 0
x = 40 or x = 17
When x = 40
57 – x = 57 – 40 = 17
When x = 17
57 – x = 57 – 17 = 40
Hence the required parts are 17 and 40.
Divide 27 into two parts such that the sum of their reciprocals is 3/20.
Let the two parts be x and (27 – x)
According to given condition,
On taking the LCM
On Cross multiplying
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 27 c = 180
= 1. – 180 = – 180
And either of their sum or difference = b
= – 27
Thus the two terms are – 15 and – 12
Sum = – 15 – 12 = – 27
Product = – 15. – 12 = 180
x (x – 15) – 12(x – 15) = 0
(x – 15) (x – 12) = 0
(x – 15) = 0 or (x – 12) = 0
x = 15 or x = 12
Case I: when x = 12
27 – x = 27 – 12 = 15
Case II: when x = 15
27 – x = 27 – 15 = 12
Hence required numbers are 12 and 15.
Divide 16 into two parts such that twice the square of the larger part exceeds the square of the smaller part by 164.
Let the larger and the smaller parts be x and y respectively.
According to the question
x + y = 16 – – – – – (1)
2x2 = y2 + 164 – – – (2)
From (1) x = 16 – y – – – (3)
From (2) and (3) we get
2(16 – y)2 = y2 + 164
2(256 – 32y + y2) = y2 + 164 using (a + b)2 = a2 + 2ab + b2
512 – 64y + 2y2 = y2 + 164
y2 – 64y + 348 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 64 c = 348
= 1. 348 = 348
And either of their sum or difference = b
= – 64
Thus the two terms are – 58 and – 6
Sum = – 58 – 6 = – 64
Product = – 58. – 6 = 348
y2 – 64y + 348 = 0
y2 – 58y – 6y + 348 = 0
y(y – 58) – 6(y – 58) = 0
(y – 58) (y – 6) = 0
(y – 58) = 0 or (y – 6) = 0
y = 6 (y < 16)
putting the value of y in (3), we get
x = 16 – 6
= 10
Hence the two natural numbers are 6 and 10.
Find two natural numbers, the sum of whose squares is 25 times their sum and also equal to 50 times their difference.
Let the two natural numbers be x and y.
According to the question
x2 + y2 = 25(x + y) – – – – – (1)
x2 + y2 = 50(x – y) – – – – (2)
From (1) and (2) we get
25(x + y) = 50(x – y)
x + y = 2(x – y)
x + y = 2x – 2y
y + 2y = 2x – x
3y = x – – – – – (3)
From (2) and (3) we get
(3y)2 + y2 = 50(3y – y)
9y2 + y2 = 50(3y – y)
10 y2 = 100y
y = 10
From (3) we have,
x = 3y = 3.10 = 30
Hence the two natural numbers are 30 and 10.
The difference of the squares of two natural numbers is 45. The square of the smaller number is four times the larger number. Find the numbers.
Let the larger number be x and smaller number be y.
According to the question
x2 – y2 = 45 – – – – – (1)
y2 = 4x – – – – – – (2)
From (1) and (2) we get
x2 – 4x = 45
x2 – 4x – 45 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 4 c = – 45
= 1. – 45 = – 45
And either of their sum or difference = b
= – 4
Thus the two terms are – 9 and 5
Sum = – 9 + 5 = – 4
Product = – 9.5 = – 45
x2 – 9x + 5x – 45 = 0
x(x – 9) + 5(x – 9) = 0
(x + 5) (x – 9) = 0
(x + 5) = 0 or (x – 9) = 0
x = – 5 or x = 9
x = 9
putting the value of x in equation (2), we get
y2 = 4.9 = 36
taking square root
y = 6
Hence the two numbers are 9 and 6
Three consecutive positive integers are such that the sum of the square of the first and the product of the other two is 46. Find the integers.
Let the three consecutive positive integers be x, x + 1, x + 2
According to the given condition,
x2 + (x + 1)(x + 2) = 46
x2 + x2 + 3x + 2 = 46
2x2 + 3x – 44 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 2 b = 3 c = – 44
= 2. – 44 = – 88
And either of their sum or difference = b
= 3
Thus the two terms are 11 and – 8
Sum = 11 – 8 = 3
Product = 11. – 8 = – 88
2x2 + 3x – 44 = 0
2x2 + 11x – 8x – 44 = 0
x(2x + 11) – 4(2x + 11) = 0
(2x + 11)(x – 4) = 0
x = 4 or – 11/2
x = 4 (x is a positive integers)
When x = 4
x + 1 = 4 + 1 = 5
x + 2 = 4 + 2 = 6
Hence the required integers are 4, 5, 6
A two – digit number is 4 times the sum of its digits and twice the product of its digits. Find the number.
Let the digits at units and tens places be x and y respectively.
Original number = 10y + x
According to the question
10y + x = 4(x + y)
10y + x = 4x + 4y
3x – 6y = 0
x = 2y – – – – (1)
also,
10y + x = 2xy
Using (1)
10y + 2y = 2.2y.y
12y = 4y2
y = 3
From (1) we get
x = 2.3 = 6
Original number = 10y + x
= (10.3) + 6 = 36
A two – digit number is such that the product of its digits is 14. If 45 is added to the number, the digits interchange their places. Find the number.
Let the digits at units and tens place be x and y respectively
xy = 14
– – – – (1)
According to the question
(10y + x) + 45 = 10x + y
9y – 9x = – 45
y – x = – 5 – – – – – (2)
From (1) and (2) we get
14 – x2 = – 5x
x2 – 5x – 14 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 5 c = – 14
= 1. – 14 = – 14
And either of their sum or difference = b
= – 5
Thus the two terms are – 7 and 2
Difference = – 7 + 2 = – 5
Product = – 7.2 = – 14
x2 – 5x – 14 = 0
x2 – 7x + 2x – 14 = 0
x(x – 7) + 2(x – 7) = 0
(x + 2)(x – 7) = 0
x = 7 or x = – 2
x = 7 (neglecting the negative part)
Putting x = 7 in equation (1) we get
y = 2
Required number = 10.2 + 7 = 27
The denominator of a fraction is 3 more than its numerator. The sum of the fraction and its reciprocal is . Find the fraction.
Let the numerator be x
Denominator = x + 3
Original number =
On taking the LCM
{ using (a + b)2 = a2 + 2ab + b2}
29x2 + 87x = 20x2 + 60x + 90
9x2 + 27x – 90 = 0
9(x2 + 3x – 10) = 0
x2 + 3x – 10 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 3 c = – 10
= 1. – 10 = – 10
And either of their sum or difference = b
= 3
Thus the two terms are 5 and – 2
Difference = 5 – 2 = 3
Product = 5. – 2 = – 10
x2 + 5x – 2x – 10 = 0
x(x + 5) – 2(x + 5) = 0
(x + 5)(x – 2) = 0
(x + 5) = 0 or (x – 2) = 0
x = 2 or x = – 5
x = 2 (rejecting the negative value)
So numerator is 2
Denominator = x + 3 = 2 + 3 = 5
So required fraction is 2/5
The numerator of a fraction is 3 less than its denominator. If 1 is added to the denominator, the fraction is decreased by . Find the fraction.
Let the denominator of required fraction be x
Numerator of required fraction be = x – 3
Original number =
If 1 is added to the denominator, then the new fraction will become
According to the given condition,
x2 + x = 15x – 45
x2 – 14x + 45 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 14 c = 45
= 1.45 = 45
And either of their sum or difference = b
= – 14
Thus the two terms are – 9 and – 5
Sum = – 9 – 5 = – 14
Product = – 9. – 5 = – 45
x2 – 14x + 45 = 0
x2 – 9x – 5x + 45 = 0
x(x – 9) – 5(x – 9) = 0
(x – 9)(x – 5) = 0
x = 9 or x = 5
Case I: x = 5
Case II: x = 9
(Rejected because this does not satisfy the condition given)
Hence the required fraction is
The sum of a number and its reciprocal is . Find the number.
Let the required number be x.
According to the given condition,
30x2 + 30 = 61x
30x2 – 61x + 30 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 30 b = – 61 c = 30
= 30.30 = 900
And either of their sum or difference = b
= – 61
Thus the two terms are – 36 and – 25
Sum = – 36 – 25 = – 61
Product = – 36. – 25 = 900
30x2 – 36x – 25x + 30 = 0
6x(5x – 6) – 5(5x – 6) = 0
(5x – 6) (6x – 5) = 0
(5x – 6) = 0 or (6x – 5) = 0
Hence the required number is
A teacher on attempting to arrange the students for mass drill in the form of a solid square found that 24 students were left. When he increased the size of the square by one student, he found that he was short of 25 students. Find the number of students.
Let there be x rows
Then the number of students in each row will also be x
Total number of students x2 + 24
According to the question,
(x + 1)2 – 25 = x2 + 24 using (a + b)2 = a2 + 2ab + b2
x2 + 2x + 1 – 25 – x2 – 24 = 0
2x – 48 = 0
x = 24
Total number of students = 242 + 24 = 576 + 24 = 600
300 apples are distributed equally among a certain number of students. Had there been 10 more students, each would have received one apple less. Find the number of students.
Let the total number of students be x
According to the question
taking LCM
cross multiplying
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 10 c = – 3000
= 1. – 3000 = – 3000
And either of their sum or difference = b
= 10
Thus the two terms are 60 and – 50
Difference = 60 – 50 = 10
Product = 60. – 50 = – 3000
x2 + 60x – 50x – 3000 = 0
x(x + 60) – 50(x + 60) = 0
(x + 60) (x – 50) = 0
(x – 50) = 0 or (x + 60) = 0
x = 50 or x = – 60
x cannot be negative thus total number of students = 50
In a class test, the sum of Kamal's marks in mathematics and English is 40. Had he got 3 marks more in mathematics and 4 marks less in English, the product of the marks would have been 360. Find his marks in two subjects separately.
Let Kamal's marks in mathematics and English be x and y, respectively
According to the question
x + y = 40 – – – – – – – (1)
Also (x + 3)(y – 4) = 360
(x + 3)(40 – x – 4) = 360 from (1)
(x + 3)(36 – x) = 360
36x – x2 + 108 – 3x = 360
33x – x2 – 252 = 0
x2 – 33x + 252 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 33 c = 252
= 1. – 252 = 252
And either of their sum or difference = b
= – 33
Thus the two terms are – 21 and – 12
Sum = – 21 – 12 = – 33
Product = – 21. – 12 = 252
x2 – 33x + 252 = 0
x2 – 21x – 12x + 252 = 0
x(x – 21) – 12(x – 21) = 0
(x – 21) (x – 12) = 0
(x – 21) = 0 or (x – 12) = 0
x = 21 or x = 12
if x = 21
y = 40 – 21 = 19
Kamal's marks in mathematics and English are 21 and 19
if x = 12
y = 40 – 12 = 28
Kamal's marks in mathematics and English are 12 and 28
Some students planned a picnic. The total budget for food was Rs. 2000. But, 5 students failed to attend the picnic and thus the cost for food for each member increased by Rs. 20. How many students attended the picnic and how much did each student pay for the food?
Let x be the number of students who planned picnic
Original cost of food for each member =
5 students failed to attend the picnic, so (x – 5) students attended the picnic
New cost of food for each member =
According to the question
taking LCM
x2 – 5x = 500 cross multiplying
x2 – 5x – 500 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 5 c = – 500
= 1. – 500 = – 500
And either of their sum or difference = b
= – 5
Thus the two terms are – 25 and 20
Sum = – 25 + 20 = – 5
Product = – 25.20 = – 500
x2 – 5x – 500 = 0
x2 – 25x + 20x – 500 = 0
x(x – 25) + 20(x – 25) = 0
(x + 20) (x – 25) = 0
(x + 20) = 0 or (x – 25) = 0
x = – 20 or x = 25
x cannot be negative thus x = 25
The number of students who planned picnic = x – 5 = 25 – 5 = 20
Cost of food for each member =
If the price of a book is reduced by Rs. 5, a person can buy 4 more books for Rs. 600. Find the original price of the book.
Let the original price of the book be Rs x
Number of books bought at original price for 600 =
If the price of a book is reduced by Rs. 5, then new price of book is Rs (x – 5)
Number of books bought at reduced price =
According to the question – –
x2 – 5x = 750
x2 – 5x – 750 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 5 c = – 750
= 1. – 750 = – 750
And either of their sum or difference = b
= – 5
Thus the two terms are – 30 and 25
Difference = – 30 + 25 = – 5
Product = – 30.25 = – 750
x2 – 5x – 750 = 0
x2 – 30x + 25x – 750 = 0
x(x – 30) + 25(x – 30) = 0
(x + 25) (x – 30) = 0
(x + 25) = 0 or (x – 30) = 0
x = – 25 , x = 30
x = 30 (Price cannot be negative)
Hence the original price of the book is Rs 30.
A person on tour has Rs. 10800 for his expenses. If he extends his tour by 4 days, he has to cut down his daily expenses by Rs. 90. Find the original duration of the tour.
Let the original duration of the tour be x days
Original daily expenses =
If he extends his tour by 4 days his daily expenses =
According to the question – –
taking LCM
x2 + 4x = 480 cross multiplying
x2 + 4x – 480 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 4 c = – 480
= 1. – 480 = – 480
And either of their sum or difference = b
= 4
Thus the two terms are 24 and – 20
Difference = 24 – 20 = 4
Product = 24. – 20 = – 480
x2 + 24x – 20x – 480 = 0
x(x + 24) – 20(x + 24) = 0
(x + 24) (x – 20) = 0
(x + 24) = 0 or (x – 20) = 0
x = – 24, x = 20
x = 20 (number of days cannot be negative)
Hence the original price of tour is 20 days
In a class test, the sum of the marks obtained by P in mathematics and science is 28. Had he got 3 more marks in mathematics and 4 marks less in science, the product of marks obtained in the two subjects would have been 180. Find the marks obtained by him in the two subjects separately.
Let the marks obtained by P in mathematics and science be x and (28 – x) respectively
According to the given condition,
(x + 3)(28 – x – 4) = 180
(x + 3)(24 – x) = 180
– x2 + 21x + 72 = 180
x2 – 21x + 108 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 21 c = 108
= 1.108 = 108
And either of their sum or difference = b
= – 21
Thus the two terms are – 12 and – 9
Difference = – 12 – 9 = – 21
Product = – 12. – 9 = 108
x2 – 12x – 9x + 108 = 0
x (x – 12) – 9 (x – 12) = 0
(x – 12) (x – 9) = 0
(x – 12) = 0 or (x – 9) = 0
x = 12, x = 9
When x = 12,
28 – x = 28 – 12 = 16
When x = 9,
28 – x = 28 – 9 = 19
Hence he obtained 12 marks in mathematics and 16 science or
He obtained 9 marks in mathematics and 19 science.
A man buys a number of pens for Rs. 180. If he had bought 3 more pens for the same amount, each pen would have cost him Rs. 3 less. How many pens did he buy?
Let the total number of pens be x
According to the question – –
taking LCM
540 = 3x2 + 9x cross multiplying
3x2 + 9x – 540 = 0
x2 + 3x – 180 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 3 c = – 180
= 1. – 108 = – 180
And either of their sum or difference = b
= 3
Thus the two terms are 15 and – 12
Difference = 15 – 12 = 3
Product = 15. – 12 = – 180
x2 + 15x – 12x – 180 = 0
x(x + 15) – 12(x + 15) = 0
(x + 15)(x – 12) = 0
(x + 15) = 0 or (x – 12) = 0
x = – 15, x = 12
x = 12 (Total number of pens cannot be negative)
Hence the Total number of pens is 12
A dealer sells an article for Rs. 75 and gains as much per cent as the cost price of the article. Find the cost price of the article.
Let the cost price of the article be x
Gain percent x%
According to the given condition,
(cost price + gain = selling price)
taking LCM
by cross multiplyingx2 + 100x = 7500
x2 + 100x – 7500 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 100 c = – 7500
= 1. – 7500 = – 7500
And either of their sum or difference = b
= 100
Thus the two terms are 150 and – 50
Difference = 150 – 50 = 100
Product = 150. – 50 = – 7500
x2 + 150x – 50x – 7500 = 0
x(x + 150) – 50(x + 150) = 0
(x + 150) (x – 50) = 0
(x + 150) = 0 or (x – 50) = 0
x = 50 (x ≠ - 150 as price cannot be negative)
Hence the cost price of the article is Rs 50
One year ago, a man was 8 times as old as his son. Now, his age is equal to the square of his son's age. Find their present ages.
Let the present age of son be x years
The present age of man = x2 years
One year ago age of son = (x – 1)years
age of man = (x2 – 1)years
According to given question, One year ago, a man was 8 times as old as his son
x2 – 1 = 8(x – 1)
x2 – 1 = 8x – 8
x2 – 8x + 7 = 0
x2 – 7x – x + 7 = 0
x(x – 7) – 1(x – 7) = 0
(x – 7) (x – 1) = 0
x = 1 or x = 7
Man’s age cannot be 1 year
Thus x = 7
Thus the present age of son is 7 years
The present age of man is 72 = 49 years
The sum of the reciprocals of Meena's ages (in years) 3 years ago and 5 years hence is 1/3. Find her present age.
Let the present age of Meena be x years
Meena’s age three years ago = (x – 3) years
Meena’s age five years hence = (x + 5) years
According to given question
x2 + 2x – 15 = 6x + 6
x2 – 4x – 21 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 4 c = – 21
= 1. – 21 = – 21
And either of their sum or difference = b
= – 4
Thus the two terms are – 7 and 3
Sum = – 7 + 3 = – 4
Product = – 7.3 = – 21
x2 – 7x + 3x – 21 = 0
x (x – 7) + 3(x – 7) = 0
(x – 7) (x + 3) = 0
x = – 3 or x = 7
x = 7 age cannot be negative
Hence the present age of Meena is 7 years
The sum of the ages of a boy and his brother is 25 years, and the product of their ages in years is 126. Find their ages.
Let the present age of boy and his brother be x years and (25 – x) years
According to given question
x(25 – x) = 126
25x – x2 = 126
x2 – 25x + 126 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 25 c = 126
= 1.126 = 126
And either of their sum or difference = b
= – 25
Thus the two terms are – 18 and – 7
Sum = – 18 – 7 = – 25
Product = – 18. – 7 = 126
x2 – 18x – 7x + 126 = 0
x (x – 18) – 7(x – 18) = 0
(x – 18) (x – 7) = 0
x = 18 or x = 7
x = 18 (Present age of boy cannot be less than his brother)
if x = 18
The present age of boy is 18 years and his brother is (25 – 18) = 7years
The product of Tanvy's age (in years) 5 years ago and her age 8 years later is 30. Find her present age.
Let the present age of Tanvy be x years
Tanvy’s age five years ago = (x – 5) years
Tanvy’s age eight years from now = (x + 8) years
(x – 5)(x + 8) = 30
x2 + 3x – 40 = 30
x2 + 3x – 70 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 3 c = – 70
= 1. – 70 = – 70
And either of their sum or difference = b
= 3
Thus the two terms are 10 and – 7
Difference = 10 – 7 = 3
Product = 10. – 7 = – 70
x2 + 10x – 7x – 70 = 0
x (x + 10) – 7(x + 10) = 0
(x + 10) (x – 7) = 0
x = – 10 or x = 7 (age cannot be negative)
x = 7
The present age of Tanvy is 7 years
Two years ago, a man's age was three times the square of his son's age. In three years’ time, his age will be four times his son's age. Find their present ages.
Let son’s age 2 years ago be x years, Then
man’s age 2 years ago be 3x2 years
son’s present age = (x + 2) years
man’s present age = (3x2 + 2)years
In three years’ time :
son’s age = (x + 2 + 3) = (x + 5) years
man’s age = (3x2 + 2 + 3)years = (3x2 + 5) years
According to question
Man’s age = 4 son’s age
3x2 + 5 = 4(x + 5)
3x2 + 5 = 4x + 20
3x2 – 4x – 15 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 3 b = – 4 c = – 15
= 3. – 15 = – 45
And either of their sum or difference = b
= – 4
Thus the two terms are – 9 and 5
Difference = – 9 + 5 = – 4
Product = – 9.5 = – 45
3x2 – 9x + 5x – 15 = 0
3x(x – 3) + 5(x – 3) = 0
(x – 3) (3x + 5) = 0
(x – 3) = 0 or (3x + 5) = 0
x = 3 or x = – 5/3 (age cannot be negative)
x = 3
son’s present age = (3 + 2) = 5years
man’s present age = (3.32 + 2) = 29years
A truck covers a distance of 150 km at a certain average speed and then covers another 200 km at an average speed which is 20 km per hour more than the first speed. If the truck covers the total distance in 5 hours, find the first speed of the truck.
Let the first speed of the truck be x km/h
Time taken to cover 150 km =
New speed of truck = x + 20 km/h
Time taken to cover 200 km =
According to given question
350x + 3000 = 5(x2 + 20x)
350x + 3000 = 5x2 + 100x
5x2 – 250x – 3000 = 0
x2 – 50x – 600 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 50 c = – 600
= 1. – 600 = – 600
And either of their sum or difference = b
= – 50
Thus the two terms are – 60 and 10
Difference = – 60 + 10 = – 50
Product = – 60.10 = – 600
x2 – 60x + 10x – 600 = 0
x (x – 60) + 10(x – 60) = 0
(x – 60) (x + 10) = 0
x = 60 or x = – 10
x = 60 (speed cannot be negative)
Hence the first speed of the truck is 60 km/hr
While boarding an aeroplane, a passenger got hurt. The pilot showing promptness and concern, made arrangements to hospitalize the injured and so the plane started late by 30 minutes. To reach the destination, 1500 km away, in time, the pilot increased the speed by 100 km/hour. Find the original speed of the plane. Do you appreciate the values shown by the pilot, namely promptness in providing help to the injured and his efforts to reach in time?
Let the original speed of the plane be x km/h
Actual speed of the plane = (x + 100) km/h
Distance of journey = 1500km
Time taken to reach destination at original speed =
Time taken to reach destination at actual speed =
According to given question
30 mins = 1/2 hr
x2 + 100x = 300000
x2 + 100x – 300000 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 100 c = – 300000
= 1. – 300000 = – 300000
And either of their sum or difference = b
= 100
Thus the two terms are 600 and – 500
Difference = 600 – 500 = 100
Product = 600. – 500 = – 300000
x2 + 600x – 500x + 300000 = 0
x (x + 600) – 500(x + 600) = 0
(x + 600)(x – 500) = 0
x = – 600 or x = 500
x = 500 (speed cannot be negative)
Hence the original speed of the plane is 500 km/hr
A train covers a distance of 480 km at a uniform speed. If the speed had been 8 km/hr less then it would have taken 3 hours more to cover the same distance. Find the usual speed of the train.
Let the usual speed of the train be x km/h
Reduced speed of the train = (x – 8) km/h
Distance of journey = 480km
Time taken to reach destination at usual speed =
Time taken to reach destination at reduced speed =
According to given question
⇒
⇒
⇒
⇒ x2 – 8x = 1280
⇒ x2 – 8x – 1280 = 0
⇒ x2 – 40x + 32x – 1280 = 0
⇒ x(x – 40) + 32(x – 40) = 0
⇒ (x – 40)(x + 32) = 0
⇒ x = 40 or x = – 32
⇒ x = 40 (speed cannot be negative)
Hence the usual speed of the train is 40 km/h
A train travels at a certain average speed for a distance of 54 km and then travels a distance of 63 km at an average speed of 6 km/hr more than the first speed. If it takes 3 hours to complete the total journey, what is its first speed?
Let the first speed of the train be x km/h
Time taken to cover 54 km =
New speed of train = x + 6 km/h
Time taken to cover 63 km =
According to given question
⇒
⇒
Taking LCM
⇒ 117x + 324 = 3(x2 + 6x)
⇒ 117x + 324 = 3x2 + 18x
⇒ 3x2 – 99x – 324 = 0
⇒ x2 – 33x – 108 = 0
⇒ x2 – 36x + 3x – 108 = 0
⇒ x (x – 36) + 3(x – 36) = 0
⇒ (x – 36) (x + 3) = 0
⇒ x = 36 or x = – 3
⇒ x = 36 (speed cannot be negative)
Hence the first speed of the train is 36 km/hr
A train travels 180 km at a uniform speed. If the speed had been 9 km/hr more, it would have taken 1 hour less for the same journey. Find the speed of the train.
Let the usual speed of the train be x km/h
Time taken to cover 180 km =
New speed of train = x + 9 km/h
Time taken to cover 180 km =
According to the question
1620 = x2 + 9x
x2 + 9x – 1620 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 9 c = – 1620
= 1. – 1620 = – 1620
And either of their sum or difference = b
= 9
Thus the two terms are 45 and – 36
Difference = – 36 + 45 = 9
Product = – 36.45 = – 1620
x2 + 45x – 36x + 1620 = 0
x(x + 45) – 36(x + 45) = 0
(x + 45) (x – 36) = 0
x = – 45 or x = 36 (but x cannot be negative)
x = 36
Hence the usual speed of the train is 36 km/h
A train covers a distance of 90 km at a uniform speed. Had the speed been 15 km/hr more, it would have taken 30 minutes less for the journey. Find the original speed of the train.
Let the original speed of the train be x km/h
Time taken to cover 90 km =
New speed of train = x + 15 km/h
Time taken to cover 90 km =
According to the question
2700 = x2 + 15x
x2 + 15x – 2700 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 15 c = – 2700
= 1. – 2700 = – 2700
And either of their sum or difference = b
= 15
Thus the two terms are – 45 and 60
Difference = 60 – 45 = 15
Product = 60. – 45 = – 2700
x2 + 60x – 45x – 2700 = 0
x(x + 60) – 45(x + 60) = 0
(x + 60) (x – 45) = 0
x = – 60 or x = 45 (but x cannot be negative)
x = 45
Hence the original speed of the train is 45 km/h
A passenger train takes 2 hours less for a journey of 300 km if its speed is increased by 5 km/hr from its usual speed. Find its usual speed.
Let the usual speed of the train be x km/h
Time taken to cover 300 km =
New speed of train = x + 5 km/h
Time taken to cover 90 km =
According to the question
750 = x2 + 5x
x2 + 5x – 750 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 5 c = – 750
= 1. – 750 = – 750
And either of their sum or difference = b
= 5
Thus the two terms are – 25 and 30
Difference = 30 – 25 = 5
Product = 30. – 25 = – 750
x2 + 30x – 25x – 750 = 0
x(x + 30) – 25(x + 30) = 0
(x + 30) (x – 25) = 0
x = – 30 or x = 25 (but x cannot be negative)
x = 25
Hence the usual speed of the train is 25 km/h
The distance between Mumbai and Pune is 192 km. Travelling by the Deccan Queen, it takes 48 minutes less than another train. Calculate the speed of the Deccan Queen if the speeds of the two trains differ by 20 km/hr.
Let the speed of Deccan Queen be x km/h
Speed of another train = (x – 20)km/h
According to the question
taking LCM
4800 = x2 – 20x cross multiplying
x2 – 20x – 4800 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 20 c = – 4800
= 1. – 4800 = – 4800
And either of their sum or difference = b
= – 20
Thus the two terms are – 80 and 60
Difference = – 80 + 60 = – 20
Product = – 80.60 = – 4800
x2 – 80x + 60x – 4800 = 0
x(x – 80) + 60(x – 80) = 0
(x – 80) (x + 60) = 0
x = 80 or x = – 60 (but x cannot be negative)
Hence the speed of Deccan Queen is 80 km/hr
A motor boat whose speed in still water is 18 km/hr, takes 1 hour more to go 24 km upstream than to return to the same spot. Find the speed of the stream.
Let the speed of stream be x km/h
Speed of boat is 18 km/hr
⇒ Speed of boat in downstream = (18 + x)km/h
⇒ Speed of boat in upstream = (18 – x)km/h
As,⇒ Time taken by boat in upstream to travel 24 Km hours
⇒
⇒
⇒
⇒ [using (a + b)(a – b) = a2 – b2]
⇒ 324 – x2 = 48x
⇒ x2 + 48x – 324 = 0
⇒ x2 + 54x – 6x – 324 = 0
⇒ x(x + 54) – 6(x + 54) = 0
⇒ (x + 54)(x – 6) = 0
⇒ x = – 54 or x = 6
(but speed cannot be negative)
⇒ x = 6
Hence the speed of stream is 6 km/h
The speed of a boat in still water is 8 km/hr. It can go 15 km upstream and 22 km downstream in 5 hours. Find the speed of the stream.
Let the speed of stream be x km/h
Speed of boat is 8 km/hr
Speed downstream = (8 + x)km/h
Speed upstream = (8 – x)km/h
296 – 7x = 320 – 5x2
5x2 – 7x – 24 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 5 b = – 7 c = – 24
= 5. – 24 = – 120
And either of their sum or difference = b
= – 7
Thus the two terms are 8 and – 15
Difference = 8 – 15 = – 7
Product = 8. – 15 = – 120
5x2 – 7x – 24 = 0
5x2 – 15x + 8x – 24 = 0
5x(x – 3) + 8(x – 3) = 0
(5x + 8)(x – 3) = 0
x = 3 or x = – 8/5
(but x cannot be negative)
x = 3
Hence the speed of stream is 3 km/hr
A motorboat whose speed is 9 km/hr in still water, goes 15 km downstream and comes back in a total time of 3 hours 45 minutes. Find the speed of the stream.
Let the speed of stream be x km/h
Speed of boat is 9km/hr
Speed downstream = (9 + x)km/h
Speed upstream = (9 – x)km/h
Distance covered downstream = Distance covered upstream = 15km
Total time taken = 3 hours 45 minutes
taking LCM
81 – x2 = 72 cross multiplying
x2 = 81 – 72
x2 = 9 taking square root
x = 3 or – 3 (rejecting negative value)
Hence the speed of stream is 3 km/hr
A takes 10 days less than the time taken by B to finish a piece of work. If both A and B together can finish the work in 12 days, find the time taken by B to finish the work.
Let B take x days to complete the work
Work one by B in one day
A will take (x – 10) days to complete the work
Work one by B in one day
According to the question
x2 – 10x = 12 (2x – 10)
x2 – 10x = 24x – 120
x2 – 34x + 120 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 34 c = 120
= 1.120 = 120
And either of their sum or difference = b
= – 34
Thus the two terms are – 30 and – 4
Sum = – 30 – 4 = – 34
Product = – 30. – 4 = 120
x2 – 30x – 4x + 120 = 0
x(x – 30) – 4(x – 30) = 0
(x – 30) (x – 4) = 0
x = 30 or x = 4
x = 30 (number of days to complete the work by B cannot be less than A)
B completes the work in 30 days
Two pipes running together can fill a cistern in minutes. If one pipe takes 3 minutes more than the other to fill it, find the time in which each pipe would fill the cistern.
Let one pipe fills a cistern in x mins.
Other pipe fills the cistern in (x + 3) mins.
Running together can fill a cistern in minutes = 40/13 mins
Part filled by one pipe in 1min =
Part filled by other pipe in 1min =
Part filled by both pipes Running together in 1min =
13x2 + 39x = 80x + 120
13x2 – 41x – 120 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 13 b = – 41 c = – 120
= 13. – 120 = – 1560
And either of their sum or difference = b
= – 41
Thus the two terms are – 65 and 24
Difference = – 65 + 24 = – 41
Product = – 65.24 = – 1560
13x2 – 65x + 24x – 120 = 0
13x(x – 5) + 24(x – 5) = 0
(x – 5) (13x + 24) = 0
(x – 5) = 0 (13x + 24) = 0
x = 5 or x = – 24/13
x = 5 (speed cannot be negative fraction)
Hence one pipe fills a cistern in 5 minutes and other pipe fills the cistern in (5 + 3) = 8 minutes.
Two pipes running together can fill a tank in minutes. If one pipe takes 5 minutes more than the other to fill the tank separately, find the time in which each pipe would fill the tank separately.
Let the time taken by one pipe to fill the tank be x minutes
The time taken by other pipe to fill the tank = x + 5 minutes
Volume of tank be V
Volume of tank filled by one pipe in x minutes = V
Volume of tank filled by one pipe in 1 minutes = V/x
Volume of tank filled by one pipe in minutes =
Volume of tank filled by other pipe in minutes =
Volume of tank filled by one pipe in minutes + Volume of tank filled by other pipe in minutes = V
200x + 500 = 9x2 + 45x
9x2 – 155x – 500 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 9 b = – 155 c = – 500
= 9. – 500 = – 4500
And either of their sum or difference = b
= – 155
Thus the two terms are – 180 and 25
Difference = – 180 + 25 = – 155
Product = – 180.25 = – 4500
9x2 – 180x + 25x – 500 = 0
9x(x – 20) + 25(x – 20) = 0
(x – 20) (9x + 25) = 0
(x – 20) = 0 (9x + 25) = 0
x = 20 or x = – 25/9
x = 20 (time cannot be negative fraction)
Hence one pipe fills the tank in 20 mins. and other pipe fills the cistern in (20 + 5) = 25 mins
Two water taps together can fill a tank in 6 hours. The tap of larger diameter takes 9 hours less than the smaller one to fill the tank separately. Find the time in which each tap can separately fill the tank.
Let the time taken by tap of smaller diameter to fill the tank be x hours
The time taken by tap of larger diameter to fill the tank = x – 9 hours
Let the volume of the tank be V
Volume of tank filled by tap of smaller diameter in x hours = V
⇒ Volume of tank filled by tap of smaller diameter in 1 hour = V/x
⇒ Volume of tank filled by tap of smaller diameter in 6 hours =
Similarly, Volume of tank filled by tap of larger diameter in 6 hours =
Volume of tank filled by tap of smaller diameter in 6 hours + Volume of tank filled by tap of larger diameter in 6 hours = V
⇒
⇒
⇒
⇒ 12x – 54 = x2 – 9x
⇒ x2 – 21x + 54 = 0
⇒ x2 – 18x – 3x + 54 = 0
⇒ x(x – 18) – 3(x – 18) = 0
⇒ (x – 18)(x – 3) = 0
⇒ (x – 18) = 0 and (x – 3) = 0
⇒ x = 18 or x = 3
For x = 3, time taken by tap of larger diameter is negative which is not possible
Thus, x = 18
Hence the time taken by tap of smaller diameter to fill the tank be 18 hours
The time taken by tap of larger diameter to fill the tank = 18 – 9 = 9hours
The length of a rectangle is twice its breadth and its area is 288 cm2. Find the dimensions of the rectangle.
Let the length and breadth of a rectangle be 2x and x respectively
According to the question;
Area = 288 cm2
Area = length.breadth
x(2x) = 288 cm2
2x2 = 288
x2 = 144
x = 12 or x = – 12
x = 12 ( x cannot be negative)
length = 2.12 = 24 cm, breadth = 12 cm
The length of a rectangular field is three times its breadth. If the area of the field be 147 sq metres, find the length of the field.
Let the length and breadth of a rectangle be 3x and x respectively
According to the question;
Area = 147cm2
Area = length.breadth
x (3x) = 147cm2
3x2 = 147
x2 = 49
x = 7 or x = – 7 taking square root both sides
x = 7 (x cannot be negative)
length = 3.7 = 21cm, breadth = 7cm
The length of a hall is 3 meters more than its breadth. If the area of the hall is 238 sq metres, calculate its length and breadth.
Let the breadth of hall be x m
The length of hall will be (x + 3) m
According to the question;
Area = 238cm2
Area = length .breadth
x2 + 3x – 238 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 3 c = – 238
= 1. – 238 = – 238
And either of their sum or difference = b
= 3
Thus the two terms are 17 and – 14
Difference = 17 – 14 = 3
Product = 17. – 14 = – 238
x2 + 17x – 14x – 238 = 0
x(x + 17) – 14(x + 17) = 0
(x + 17) (x – 14) = 0
x = – 17 or x = 14
x = 14 ( x cannot be negative)
Hence the breadth of hall is 14 m and the length of hall is (14 + 3) = 17m
The perimeter of a rectangular plot is 62 m and its area is 228 sq meters. Find the dimensions of the plot.
Let the length and breadth of rectangular plot be x and y respectively.
Perimeter = 2(x + y) = 62 – – – – – (1)
Area = xy = 228
y = 228/x
Putting the value of y in 1
taking LCM
x2 + 228 = 31x cross multiplying
x2 – 31x + 288 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = – 31 c = 288
= 1.288 = 288
And either of their sum or difference = b
= – 31
Thus the two terms are – 19 and – 12
Difference = – 19 – 12 = – 31
Product = – 19. – 12 = 288
x2 – 19x – 12x + 288 = 0
x(x – 19) – 12(x – 19) = 0
(x – 19) (x – 12) = 0
x = 19 or x = 12
if x = 19
if x = 12
length is 19m and breadth is 12m
length is 12m and breadth is 19m
A rectangular field is 16 m long and 10 m wide. There is a path of uniform width all around it, having an area of 120 m2. Find the width of the path.
Let the width of the path be x m
Length of the field including the path = 16 + x + x = 16 + 2x
Breadth of the field including the path = 10 + x + x = 10 + 2x
Area of field including the path – Area of field excluding the path = Area of path
(16 + 2x) (10 + 2x) – (16.10) = 120
160 + 32x + 20x + 4x2 – 160 = 120
4x2 + 52x – 120 = 0
x2 + 13x – 30 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 13 c = – 30
= 1. – 30 = – 30
And either of their sum or difference = b
= 13
Thus the two terms are 15 and – 2
Difference = 15 – 2 = 13
Product = 15. – 2 = – 30
x2 + 15x – 2x – 30 = 0
x(x + 15) – 2(x + 15) = 0
(x + 15) (x – 2) = 0
x = 2 or x = – 15
x = 2 (width cannot be negative)
Thus the width of the path is 2 m
The sum of the areas of two squares is 640 m2. If the difference in their perimeters be 64 m, find the sides of the two squares.
Let the length of first and second square be x and y respectively
According to the question;
x2 + y2 = 640 – – – – (1)
Also 4x – 4y = 64
x – y = 16
x = 16 + y
Putting the value of x in(1) we get
(16 + y)2 + y2 = 640 using (a + b)2 = a2 + 2ab + b2
256 + 32y + y2 + y2 = 640
2y2 + 32y – 384 = 0
y2 + 16y – 192 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 16 c = – 192
= 1. – 192 = – 192
And either of their sum or difference = b
= 16
Thus the two terms are 24 and – 8
Difference = 24 – 8 = 16
Product = 24. – 8 = 192
y2 + 24y – 8y – 192 = 0
y(y + 24) – 8(y + 24) = 0
(y + 24) (y – 8) = 0
(y + 24) = 0 (y – 8) = 0
y = 8 or y = – 24
y = 8 (y cannot be negative)
x = 16 + 8 = 24m
Hence the length of first square is 24m and second square is 8m.
The length of a rectangle is thrice as long as the side of a square. The side of the square is 4 cm more than the width of the rectangle. Their areas being equal, find their dimensions.
Let the breadth of a rectangle be x cm
According to the question;
Side of square = (x + 4) cm
Length of a rectangle = [3(x + 4)] cm
Area of rectangle and square are equal – –
3(x + 4)x = (x + 4)2
3x2 + 12x = (x + 4)2
3x2 + 12x = x2 + 8x + 16 { using (a + b)2 = a2 + 2ab + b2}
2x2 + 4x – 16 = 0
x2 + 2x – 8 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 2 c = – 8
= 1. – 8 = – 8
And either of their sum or difference = b
= 2
Thus the two terms are 4 and – 2
Difference = 4 – 2 = 2
Product = 4. – 2 = – 8
x2 + 4x – 2x – 8 = 0
x(x + 4) – 2(x + 4) = 0
(x + 4) (x – 2) = 0
⇒ x = – 4 or x = 2
x = 2 (width cannot be negative)
Thus the breadth of a rectangle = 2 cm
Length of a rectangle = [3(x + 4)] = 3(2 + 4) = 18 cm
Side of square = (x + 4) = 2 + 4 = 6cm
A farmer prepares a rectangular vegetable garden of area 180 sq metres. With 39 metres of barbed wire, he can fence the three sides of the garden, leaving one of the longer sides unfenced. Find the dimensions of the garden.
Let the length and breadth of rectangular plot be x and y respectively.
Area = xy = 180 sq m – – – – – (1)
2(x + y) –x = 39
2x + 2y – x = 39
2y + x = 39
x = 39 – 2y
Putting the value of x in (1) we get
(39 – 2y)y = 180
39y – 2y2 = 180
2y2 – 39y + 180 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 2 b = – 39 c = 180
= 2.180 = 360
And either of their sum or difference = b
= – 39
Thus the two terms are – 24 and – 15
Difference = – 24 – 15 = – 39
Product = – 24. – 15 = 360
2y2 – 24y – 15y + 180 = 0
2y(y – 12) – 15(y – 12) = 0
(y – 12)(2y – 15) = 0
y = 12 or y = 15/2 = 7.5
if y = 12 x = 39 – 2y = 39 – (2.12) = 39 – 24 = 15
if y = 7.5 x = 39 – 2y = 39 – [(2)(7.5)] = 39 – 15 = 24
Hence either l = 24 m, b = 7.5 m or l = 15 m, b = 12 m
The area of a right triangle is 600 cm2. If the base of the triangle exceeds the altitude by 10 cm, find the dimensions of the triangle.
Let the altitude of the given triangle x cm
Thus the base of the triangle will be (x + 10)cm
Area of triangle =
x (x + 10) = 1200
x2 + 10x – 1200 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 10 c = – 1200
= 1. – 1200 = – 1200
And either of their sum or difference = b
= 10
Thus the two terms are 40 and – 30
Difference = 40 – 30 = 10
Product = 40. – 30 = – 1200
x2 + 40x – 30x – 1200 = 0
x(x + 40) – 30(x + 40) = 0
(x + 40)(x – 30) = 0
x = – 40, 30
x = 30 (altitude cannot be negative)
Thus the altitude of the given triangle is 30cm and base of the triangle = 30 + 10 = 40cm
Hypotenuse2 = altitude2 + base2
Hypotenuse2 = (30)2 + (40)2
= 900 + 1600 = 2500
Hypotenuse = 50 cm
Altitude = 30cm
Base = 40cm
The area of a right – angled triangle is 96 sq metres. If the base is three times the altitude, find the base.
Let the altitude of the triangle be x m
The base will be 3x m
Area of triangle = 1/2. Base. altitude
1/2.3x.x = 96
x2 = 64
x = 8 or – 8 taking square root
Value of x cannot be negative
Thus the altitude of the triangle be 8 m
The base will be 3.8 = 24m
The area of a right – angled triangle is 165 sq meters. Determine its base and altitude if the latter exceeds the former by 7 meters.
Let the base be x m
The altitude will be x + 7 m
Area of triangle = 1/2 base. altitude
= 1/2 x (x + 7) = 165
x2 + 7x = 330
x2 + 7x – 330 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 7 c = – 330
= 1. – 330 = – 330
And either of their sum or difference = b
= 7
Thus the two terms are 22 and – 15
Difference = 22 – 15 = 7
Product = 22. – 15 = – 330
x2 + 22x – 15x – 330 = 0
x(x + 22) – 15(x + 22) = 0
(x + 22) (x – 15) = 0
x = – 22 or x = 15
Value of x cannot be negative
x = 15
Thus the base be 15m and altitude = 15 + 7 = 22m
The hypotenuse of a right – angled triangle is 20 meters. If the difference between the lengths of the other side’s be 4 meters, find the other sides.
Let one side of right – angled triangle be x m and other side be x + 4 m
On applying the Pythagoras theorem –
202 = (x + 4)2 + x2
400 = x2 + 8x + 16 + x2
400 = 2x2 + 8x + 16
2x2 + 8x – 384 = 0
x2 + 4x – 192 = 0
Using the splitting middle term – the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 4 c = – 192
= 1. – 192 = – 192
And either of their sum or difference = b
= 4
Thus the two terms are 16 and – 12
Difference = 16 – 12 = 4
Product = 16. – 12 = – 192
x2 + 16x – 12x – 192 = 0
x(x + 16) – 12(x + 16) = 0
(x + 16) (x – 12) = 0
x = 16 or x = 12
x cannot be negative
Base is 12m and other side is 12 + 4 = 16m
The length of the hypotenuse of a right – angled triangle exceeds the length of the base by 2 cm and exceeds twice the length of the altitude by 1 cm. Find the length of each side of the triangle.
Let the base and altitude of the right angled triangle be x and y respectively.
Thus the hypotenuse of triangle will be x + 2 cm
(x + 2)2 = y2 + x2 – – – (1)
Also the hypotenuse exceeds twice the length of the altitude by 1 cm
h = 2y + 1
x + 2 = 2y + 1
x = 2y – 1
Putting the value of x in (1) we get
(2y – 1 + 2)2 = y2 + (2y – 1)2
(2y + 1)2 = y2 + 4 y2 – 4y + 1
4y2 + 4y + 1 = 5y2 – 4y + 1 using (a + b)2 = a2 + 2ab + b2
– y2 + 8y = 0
y(y – 8) = 0
y = 8
x = 16 – 1 = 15cm
h = 16 + 1 = 17cm
Thus the base, altitude, hypotenuse of triangle are 15cm, 8cm, 17cm respectively.
The hypotenuse of a right – angled triangle is 1 metre less than twice the shortest side. If the third side is 1 metre more than the shortest side, find the sides of the triangle.
Let the shortest side of triangle be xm
According to the question ;
Hypotenuse = 2x – 1 m
Third side = x + 1 m
Applying Pythagoras theorem
(2x – 1)2 = (x + 1)2 + x2
4x2 – 4x + 1 = x2 + 2x + 1 + x2 using (a – b)2 = a2 – 2ab + b2
2 x2 – 6x = 0
2x (x – 3) = 0
x = 0 or x = 3
Length of side cannot be 0 thus the shortest side is 3m
Hypotenuse = 2x – 1 = 6 – 1 = 5m
Third side = x + 1 = 3 + 1 = 4m
Thus the dimensions of triangle are 3m, 4m and 5m.
Which of the following is a quadratic equation?
A. x2 – 3√x + 2 = 0
B. x + 1/x = x2
C. x2 + 1/x2 = 5
D. 2x2 – 5x = (x – 1)2
A quadratic equation is of the form i.e. of degree 2 (a ≠ 0, a, b, c are real numbers)
A. this is not of the form hence it is not quadratic equation.
B.
This is not of the form hence it is not quadratic equation.
C.
This is not of the form hence it is not quadratic equation.
D. using
This is of the form i.e. of degree 2 (a ≠ 0, a, b, c are real numbers)
Hence this is a quadratic equation.
Which of the following is a quadratic equation?
A. (x2 + 1) = (2 – x)2 + 3
B. x3 – x2 = (x – 1)3
C. 2x2 + 3 = (5 + x)(2x – 3)
D. none of these
A. using
This is not of the form hence it is not quadratic equation.
B. using
This is of the form i.e. of degree 2 (a ≠ 0, a, b, c are real numbers)
Hence this is a quadratic equation.
Which of the following is not a quadratic equation?
A. 3x – x2 = x2 + 5
B. (x + 2)2 = 2(x2 – 5)
C. (√2x + 3)2 = 2x2 + 6
D. (x – 1)2 = 3x2 + x – 2
A.
This is a quadratic equation of the form hence i.e. of degree 2 (a ≠ 0, a, b, c are real numbers).
B.
using
This is a quadratic equation of the form i.e. of degree 2 (a ≠ 0, a, b, c are real numbers).
C. using
This is not quadratic since it is not of the form i.e. of degree 2 (a ≠ 0, a, b, c are real numbers).
D.
using
This is a quadratic equation of the form i.e. of degree 2 (a ≠ 0, a, b, c are real numbers).
If x = 3 is a solution of the equation 3x2 + (k – 1)x + 9 = 0 then k = ?
A. 11
B. - 11
C. 13
D. - 13
x = 3 is a solution of the equation means it satisfies the equation
If one root of the equation 2x2 + ax + 6 = 0 is 2 then a = ?
A. 7
B. - 7
C.
D.
One root of the equation is 2 i.e. it satisfies the equation
The sum of the roots of the equation x2 – 6x + 2 = 0 is
A. 2
B. - 2
C. 6
D. - 6
For the equation
comparing with general equation
Where α and β are the roots of the equation.
If the product of the roots of the equation x2 – 3x + k = 10 is - 2 then the value of k is
A. - 2
B. - 8
C. 8
D. 12
Given that the product of the roots of the equation is - 2
x2 - 3x + (k - 10) = 0
comparing with general equation
Product of the roots =
=
The ratio of the sum and product of the roots of the equation
7x2 - 12x + 18 = 0 is
A. 7 : 12
B. 7 : 18
C. 3 : 2
D. 2 : 3
For the given equation 7x2 - 12x + 18 = 0
a = 7 b = - 12 c = 18 comparing with ax2 + bx + c = 0
Sum of the roots
Product of the roots
Ratio of sum: product =
= 12:18 = 2:3
If one root of the equation 3x2 - 10x + 3 = 0 is 1/3 then the other root is
A.
B.
C. - 3
D. 3
For the given equation 3x2 - 10x + 3 = 0
a = 3 b = - 10 c = 3 comparing with ax2 + bx + c = 0
Product of the roots
One root of the equation is
Let other root be
If one root of 5x2 + 13x + k = 0 be the reciprocal of the other root then the value of k is
A. 0
B. 1
C. 2
D. 5
Let the roots of equation be than other root will be
Product of two roots =
Product of the roots =
For the given equation 5x2 + 13x + k = 0
a = 5 b = 13 c = k comparing with ax2 + bx + c = 0
Product of the roots
k = 5
If the sum of the roots of the equation kx2 + 2x + 3k = 0 is equal to their product then the value of k is
A.
B.
C.
D.
For the given equation kx2 + 2x + 3k = 0
a = k b = 2 c = 3k comparing with ax2 + bx + c = 0
Sum of the roots
Product of the roots
Sum of roots is equal to their product:
The roots of a quadratic equation are 5 and - 2. Then, the equation is
A. x2 - 3x + 10 = 0
B. x2 - 3x - 10 = 0
C. x2 + 3x - 10 = 0
D. x2 + 3x + 10 = 0
The roots of a quadratic equation will satisfy the equation - start with option 1
A. x2 - 3x + 10 = 0
For x = 5
52 - (3.5) + 10
25 - 15 + 10 = 20 ≠ 0
Hence this is not the equation
B. x2 - 3x - 10 = 0
For x = 5
52 - (3.5) - 10 = 25 - 15 - 10
= 25 - 25 = 0
For x = - 2
= ( - 2)2 - (3. - 2) - 10
= 4 + 6 - 10 = 10 - 10 = 0
This equation is satisfied for both the roots.
If the sum of the roots of a quadratic equation is 6 and their product is 6, the equation is
A. x2 - 6x + 6 = 0
B. x2 + 6x - 6 = 0
C. x2 - 6x - 6 = 0
D. x2 + 6x + 6 = 0
Sum = 6 and Product = 6
Quadratic equation = x2 –Sum x + Product = 0
= x2 - 6x + 6 = 0
If α and β are the roots of the equation 3x2 + 8x + 2 = 0 then = ?
A.
B.
C. - 4
D. 4
Given are the roots of the equation 3x2 + 8x + 2 = 0
For the equation a = 3 b = 8 c = 2 comparing with ax2 + bx + c = 0
Sum of roots
Product of roots
The roots of the equation ax2 + bx + c = 0 will be reciprocal of each other if
A. a = b
B. b = c
C. c = a
D. none of these
Let the roots of equation be
Product of roots =
Product of the roots
Hence c = a
If the roots of the equation ax2 + bx + c = 0 are equal then c = ?
A.
B.
C.
D.
If roots of the equation ax2 + bx + c = 0 are equal
Then D = b2 - 4ac = 0
b2 = 4ac
If the equation 9x2 + 6kx + 4 = 0 has equal roots then k = ?
A. 2 or 0
B. - 2 or 0
C. 2 or - 2
D. 0 only
The equation 9x2 + 6kx + 4 = 0 has equal roots
a = 9 b = 6k c = 4
Then D = b2 - 4ac = 0
(6k)2 - 4.9.4 = 0
36k2 = 144
k2 = 4 taking square root both sides
k = 2 or k = - 2
If the equation x2 + 2(k + 2)x + 9k = 0 has equal roots then k = ?
A. 1 or 4
B. - 1 or 4
C. 1 or - 4
D. - 1 or - 4
Given that the equation x2 + 2(k + 2)x + 9k = 0 has equal roots.
a = 1 b = 2(k + 2) c = 9k
D = b2 - 4ac = 0
(2k + 4)2 - 4.1.9k = 0
4k2 + 16 + 16k - 36k = 0
4k2 - 20k + 16 = 0
k2 - 5k + 4 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = - 5 c = 4
= 1.4 = 4
And either of their sum or difference = b
= - 5
Thus the two terms are - 4 and - 1
Difference = - 4 - 1 = - 5
Product = - 4. - 1 = 4
k2 - 4k - k + 4 = 0
k(k - 4) - 1(k - 4) = 0
(k - 4) (k - 1) = 0
k = 4 or k = 1
If the equation 4x2 - 3kx + 1 = 0 has equal roots then k = ?
A.
B.
C.
D.
Given the equation 4x2 - 3kx + 1 = 0 has equal roots
For the given equation a = 4 b = - 3k c = 1
D = b2 - 4ac = 0
( - 3k)2 - 4.4.1 = 0
9k2 - 16 = 0
9k2 = 16
k2 = 16/9
The roots of ax2 + bx + c = 0, a 0 are real and unequal, if (b2 - 4ac) is
A. > 0
B. = 0
C. < 0
D. none of these
The roots of equation are real and unequal, if (b2 - 4ac) > 0
In the equation ax2 + bx + c = 0, it is given that D = (b2 - 4ac) > 0. Then, the roots of the equation are
A. real and equal
B. real and unequal
C. imaginary
D. none of these
If for the equation ax2 + bx + c = 0, it is given that D = (b2 - 4ac) > 0 then the roots are real and unequal.
The roots of the equation 2x2 - 6x + 7 = 0 are
A. real, unequal and rational
B. real, unequal and irrational
C. real and equal
D. imaginary
For the given equation 2x2 - 6x + 7 = 0
a = 2 b = - 6 c = 7
D = b2 - 4ac
= ( - 6)2 - 4.2.7
= 36 – 56 = - 20 < 0
Thus the roots of equation are imaginary.
The roots of the equation 2x2 - 6x + 3 = 0 are
A. real, unequal and rational
B. real, unequal and irrational
C. real and equal
D. imaginary
For the given equation 2x2 - 6x + 3 = 0
a = 2 b = - 6 c = 3
D = b2 - 4ac
= ( - 6)2 - 4.2.3
= 36 - 24 = 12 > 0 this is not a perfect square hence the roots of the equation are real, unequal and irrational
If the roots of 5x2 - kx + 1 = 0 are real and distinct then
A. –2√5 < k < 2√5
B. k > 2 √5 only
C. k < - 2√5 only
D. either k > 2 √5 or k < - 2√5
Given that the roots of 5x2 - kx + 1 = 0 are real and distinct
a = 5 b = - k c = 1
D = b2 - 4ac > 0
= ( - k)2 - 4.5.1
= k2 - 20 > 0
k2 > 20
Roots are either
If the equation x2 + 5kx + 16 = 0 has no real roots then
A. k > 8/5
B. k < –8/5
C. –8/5 < k < 8/5
D. none of these
Given the equation x2 + 5kx + 16 = 0 has no real
a = 1 b = 5k c = 16
Thus D = b2 - 4ac < 0
= (5k)2 - 4.1.16 < 0
= 25k2 - 64 < 0
25k2 = 64
If the equation x2 - kx + 1 = 0 has no real roots then
A. k < - 2
B. k > 2
C. - 2 < k < 2
D. none of these
Given the equation x2 - kx + 1 = 0 has no real roots
a = 1 b = - k c = 1
Thus D = b2 - 4ac < 0
( - k)2 - 4.1.1 < 0
k2 - 4 < 0
k2 < 4
- 2 < k < 2
For what values of k, the equation kx2 - 6x - 2 = 0 has real roots?
A.
B.
C.
D. none of these
Given the equation kx2 - 6x - 2 = 0 has real roots
a = k b = - 6 c = - 2
Thus D = b2 - 4ac ≥0
( - 6)2 - 4.k. - 2 ≥0
36 + 8k ≥0
8k≥ - 36
The sum of a number and its reciprocal is . The number is
A.
B.
C.
D.
Let the required number be x
According to the question
20x2 - 41x + 20 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 20 b = - 41 c = 20
= 20.20 = 400
And either of their sum or difference = b
= - 41
Thus the two terms are - 25 and - 16
Difference = - 25 - 16 = - 41
Product = - 25. - 16 = 400
20x2 - 25x - 16x + 20 = 0
5x(4x - 5) - 4(4x - 5) = 0
(5x - 4) (4x - 5) = 0
The perimeter of a rectangle is 82 m and its area is 400 m2. The breadth of the rectangle is
A. 25 m
B. 20 m
C. 16 m
D. 9 m
Let the length and breadth of the rectangle be l and b respectively
Perimeter of a rectangle is 82 m
2(l + b) = 82
l + b = 41
l = 41 - b - - - - - - (1)
Area is 400 m2
lb = 400
(41 - b) b = 400 using (1)
41b –b2 = 400
b2 - 41b + 400 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = - 41 c = 400
= 1.400 = 400
And either of their sum or difference = b
= - 41
Thus the two terms are - 25 and - 16
Difference = - 25 - 16 = - 41
Product = - 25. - 16 = 400
b2 - 25b - 16b + 400 = 0
b(b - 25) - 16(b - 25) = 0
(b - 25) (b - 16) = 0
b = 25 or b = 16
If b = 25 l = 41 - 25 = 16 but l cannot be less than b
Thus b = 16m
The breadth of the rectangle = 16m
The length of a rectangular field exceeds its breadth by 8 m and the area of the field is 240 m2. The breadth of the field is
A. 20 m
B. 30 m
C. 12 m
D. 16 m
Let the breadth of the rectangle be x m
Thus the length of the rectangle is (x + 8) m
Area of the field is 240 m2 = length . breadth
x(x + 8) = 240
x2 + 8x - 240 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 8 c = - 240
= 1. - 240 = - 240
And either of their sum or difference = b
= 8
Thus the two terms are 20 and - 12
Difference = 20 - 12 = 8
Product = 20. - 12 = - 240
x2 + 20x - 12x - 240 = 0
x(x + 20) - 12(x + 20) = 0
(x + 20) (x - 12) = 0
x = 12 or x = - 20 (but breadth cannot be negative)
The breadth of the rectangle = 12m
The roots of the quadratic equation 2x2 - x - 6 = 0 are
A. - 2, 3/2
B. 2, –3/2
C. - 2, –3/2
D. 2, 3/2
2x2 - x - 6 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 2 b = - 1 c = - 6
= 2. - 6 = - 12
And either of their sum or difference = b
= - 1
Thus the two terms are - 4 and 3
Difference = - 4 + 3 = - 1
Product = - 4.3 = - 12
2x2 - 4x + 3x - 6 = 0
2x(x - 2) + 3(x - 2) = 0
(x - 2) (2x + 3) = 0
x = 2 x = - 3/2
The sum of two natural numbers is 8 and their product is 15. Find the numbers.
Let the required natural number be x and (8 - x)
their product is 15
x(8 - x) = 15
8x –x2 = 15
x2 - 8x + 15 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = - 8 c = 15
= 1.15 = 15
And either of their sum or difference = b
= - 8
Thus the two terms are - 5 and - 3
Sum = - 5 - 3 = - 8
Product = - 5. - 3 = 15
x2 - 5x - 3x + 15 = 0
x(x - 5) - 3(x - 5) = 0
(x - 5) (x - 3) = 0
x = 5 or x = 3
Hence the required natural numbers are 5 and 3
Show that x = - 3 is a solution of x2 + 6x + 9 = 0.
If x = - 3 is a solution then it must satisfy the equation
x2 + 6x + 9 = 0
LHS = x2 + 6x + 9
= ( - 3)2 + 6. - 3 + 9
= 9 - 18 + 9
= 18 - 18
= 0 = RHS
Thus x = - 3 is a solution of the equation
Show that x = - 2 is a solution of 3x2 + 13x + 14 = 0.
If x = - 2 is a solution then it must satisfy the equation
3x2 + 13x + 14 = 0
LHS = 3x2 + 13x + 14
= 3( - 2)2 + 13( - 2) + 14
= 12 - 26 + 14 = 26 - 26 = 0 = RHS
Thus x = - 2 is a solution of the equation
If is a solution of the quadratic equation 3x2 + 2kx - 3 = 0, find the value of k.
Given is a solution of the quadratic equation 3x2 + 2kx - 3 = 0.Thus it must satisfy the equation.
Hence the value of k is
Find the roots of the quadratic equation 2x2 - x - 6 = 0.
Given: 2x2 - x - 6 = 0
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 2 b = - 1 c = - 6
= 2. - 6 = - 12
And either of their sum or difference = b
= - 1
Thus the two terms are - 4 and 3
Sum = - 4 + 3 = - 1
Product = - 4.3 = - 12
2x2 - 4x + 3x - 6 = 0
2x(x - 2) + 3(x - 2) = 0
(x - 2) (2x + 3) = 0
x = 2 or x = - 3/2
Hence the roots of the given equation x = 2 or x =
Find the solution of the quadratic equation 3√3x2 + 10x + √3 = 0
The given
Using the splitting middle term - the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
And either of their sum or difference = b
= 10
Thus the two terms are 9 and 1
Sum = 9 + 1 = 10
Product = 9.1 = 9
using
If the roots of the quadratic equation 2x2 + 8x + k = 0 are equal then find the value of k.
The roots of the quadratic equation 2x2 + 8x + k = 0 are equal then D = 0
a = 2 b = 8 c = k
D = b2 - 4ac = 0
= 82 - 4.2.k = 0
= 64 - 8k = 0
8k = 64
k = 8
If the quadratic equation px2 –2√5px + 15 = 0 has two equal roots then find the value of p.
The quadratic equation has two equal roots
D = b2 - 4ac = 0
=
= 20p2 - 60p = 0
= 20p (p - 3) = 0
p = 0 or p = 3
For p = 0 in the equation 0 + 0 + 15 = 0 but this is not possible
Thus p0
p = 3
If 1 is a root of the equation ay2 + ay + 3 = 0 and y2 + y + b = 0 then find the value of ab.
Given that y = 1 is a root of the equation ay2 + ay + 3 = 0
a.12 + a.1 + 3 = 0
a + a + 3 = 0
2a + 3 = 0
a = - 3/2
Also y = 1 is a root of the equation y2 + y + b = 0
12 + 1 + b = 0
2 + b = 0
b = - 2
Thus the value of ab = 3
If one zero of the polynomial x2 - 4x + 1 is (2 + √3 ), write the other zero.
Given one zero of the polynomial x2 - 4x + 1 is ,
a = 1 b = - 4 c = 1
Than let the other zero of the polynomial be
Sum of zeroes
Hence the other zero of the polynomial is
If one root of the quadratic equation 3x2 - 10x + k = 0 is reciprocal of the other, find the value of k.
Let α and β be roots of the quadratic equation 3x2 - 10x + k = 0
a = 3 b = - 10 c = k
Then
For any general quadratic equation in the form ax2 + bx + c = 0, we have
Product of roots
⇒
⇒ k = 3
If the roots of the quadratic equation px(x – 2) + 6 = 0 are equal, find the value of p.
Given that the roots of the quadratic equation are equal
Comparing with general equation, for the given equation
Hence
4p(p-6) = 0
4p = 0 or (p-6) = 0
p = 0 or p = 6
Putting p = 0 in equation given we get 6 = 0 that is not possible
Hence value of p = 6 for which the equation has equal roots.
Find the values of k so that the quadratic equation x2 – 4kx + k = 0 has equal roots.
Given that the quadratic equation has equal roots
Comparing with general equation, for the given equation
Hence
Hence 0 and are values of k for which the equation has equal roots.
Find the values of k for which the quadratic equation 9x2 – 3kx + k = 0 has equal roots.
Given that the quadratic equation has equal roots
Comparing with general equation, for the given equation
Hence
Hence 0 and 4 are values of k for which the equation has equal roots.
Solve:
Using splitting middle term, the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
And either of their sum or difference = b
Thus the two terms are
Difference =
Product =
Hence the roots of given equation are
Solve: 2x2 + ax – a2 = 0
Using splitting middle term, the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
=
And either of their sum or difference = b
=
Thus the two terms are
Difference =
Product =
Hence roots of equation are
Solve: 3x2 + 5√5x – 10 = 0
Using splitting middle term, the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
=
And either of their sum or difference = b
=
Thus the two terms are
Difference =
Product = using
Hence roots of equation are
Solve: √3x2 + 10x – 8√3 = 0.
Using splitting middle term, the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
using
=
And either of their sum or difference = b
=
Thus the two terms are
Difference =
Product =
√3 x(x + 4√3 )-2(x + 4√3) = 0
(√3 x-2)(x + 4√3) = 0
Hence roots of equation are
Solve: √3x2 – 2√2x – 2√3 = 0
Using splitting middle term, the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
using
=
And either of their sum or difference = b
=
Thus the two terms are
Difference =
Product = = - 6
√3 x(x-√6) + √2(x-√6) = 0
(√3 x + √2)(x-√6) = 0
(√3 x + √2) = 0 or (x-√6) = 0
Hence roots of equation are
Solve: 4√3x2 + 5x –2√3 = 0
Using splitting middle term, the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
=
And either of their sum or difference = b
=
Thus the two terms are
Difference =
Product =
Hence roots of equation are
Solve: 4x2 + 4bx – (a2 – b2) = 0.
Using splitting middle term, the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
And either of their sum or difference = b
=
Thus the two terms are
Difference =
=
=
Product =
=
using
=
using
2x[2x + (a + b)] - (a - b)[2x + (a + b)] = 0
[2x - (a - b)][2x + (a + b)] = 0
[2x - (a - b)] = 0 or [2x + (a + b)] = 0
2x = (a - b) or 2x = - (a + b)
Hence roots of equation are
Solve: x2 + 5x – (a2 + a – 6) = 0
Using splitting middle term, the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation a = 1 b = 5 c =
=
And either of their sum or difference = b
=
Thus the two terms are
Difference =
=
Product =
=
x[x + (a + 3)] - (a - 2)[x + (a + 3)] = 0
[x - (a - 2)][x + (a + 3)] = 0
[x - (a - 2)] = 0 or [x + (a + 3)] = 0
x = (a - 2) or x = - (a + 3)
Hence roots of equation are x = (a - 2)or - (a + 3)
x2 + 6x – (a2 + 2a – 8) = 0
Using splitting middle term, the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
=
And either of their sum or difference = b
=
Thus the two terms are (a + 4) & (a-2)
Difference = (a + 4)-(a-2)
= 6
Product = (a + 4)(a-2)
=
x[x + (a + 4)]-(a-2)[x + (a + 4)] = 0
[x-(a-2)][x + (a + 4)] = 0
[x-(a-2)] = 0 or [x + (a + 4)] = 0
x = (a-2) or x = -(a + 4)
Hence roots of equation are x = (a-2) or-(a + 4)
x2 – 4ax + 4a2 – b2 = 0
Using splitting middle term, the middle term of the general equation is divided in two such values that:
Product = a.c
For the given equation
= =
And either of their sum or difference = b
=
Thus the two terms are
Sum =
=
=
Product = using
= =
x[x-(2a + b)]-(2a-b)[x-(2a + b)] = 0
[x-(2a-b)][x-(2a + b)] = 0
[x-(2a-b)] = 0 or [x-(2a + b)] = 0
x = (2a-b) or x = (2a + b)
Hence roots of equation are x = (2a - b) or x = (2a + b)