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Polynomials

Class 10th Mathematics KC Sinha Solution
Exercise 2.1
  1. Examine, seeing the graph of the polynomials given below, whether they are a…
  2. The graphs of y - p(x) are given in the figures below, where p(x) is a…
  3. The graphs of y = p(x) are given in the figures below, where p(x) is a…
Exercise 2.2
  1. x^2 - 3 Find the zeroes of the following quadratic polynomials and verify the…
  2. 2x^2 - 8x + 6 Find the zeroes of the following quadratic polynomials and verify…
  3. x^2 - 2x - 8 Find the zeroes of the following quadratic polynomials and verify…
  4. 3x^2 + 5x - 2 Find the zeroes of the following quadratic polynomials and verify…
  5. 3x^2 - x - 4 Find the zeroes of the following quadratic polynomials and verify…
  6. x^2 + 7x + 10 Find the zeroes of the following quadratic polynomials and verify…
  7. t^2 - 15 Find the zeroes of the following quadratic polynomials and verify the…
  8. 4 s^2 - 4s + 1 Find the zeroes of the following quadratic polynomials and…
  9. 8x^2 - 22x - 21 Find the zeroes of the following quadratic polynomials and…
  10. 2x^2 - 7x Find the zeroes of the following quadratic polynomials and verify the…
  11. 10x^2 + 3x - 1 Find the zeroes of the following quadratic polynomials and…
  12. px2 + (2q - p^2)x - 2pq, p≠0 Find the zeroes of the following quadratic…
  13. x^2 - (2a + b)x + 2ab Find the zeroes of the following quadratic polynomials…
  14. r^2 s^2 x^2 + 6rstx + 9t^2 Find the zeroes of the following quadratic…
  15. Find the zeroes of the quadratic polynomial 5x^2 - 8x - 4 and verify the…
  16. Find the zeroes of the quadratic polynomial 4 x^2 - 4x - 3 and verify the…
  17. Find the zeroes of the quadratic polynomial √3 x^2 - 8x + 4√3 .
  18. If α and β be the zeroes of the polynomial 2x^2 + 3x - 6, find the values of (i)…
  19. If α and β be the zeroes of the polynomial ax^2 + bx + c, find the values of (i)…
  20. If α, β are the zeroes of the quadratic polynomial x^2 + kx = 12, such that α -…
  21. If the sum of squares of the zeroes of the quadratic polynomial x^2 - 8x + k is…
  22. If one zero of the polynomial (α^2 + 9) x^2 + 13x + 6α is reciprocal of the…
  23. If the product of zeroes of the polynomial α^2 - 6x - 6 is 4, find the value of…
  24. If (x + a) is a factor 2x^2 + 2ax + 5x + 10, find a.
  25. 1,1 Find a quadratic polynomial each with the given numbers as the sum and…
  26. 0,3 Find a quadratic polynomial each with the given numbers as the sum and…
  27. 1/4 ,-1 Find a quadratic polynomial each with the given numbers as the sum and…
  28. 4,1 Find a quadratic polynomial each with the given numbers as the sum and…
  29. 10/3 ,-1 Find a quadratic polynomial each with the given numbers as the sum and…
  30. - 1/2 , - 1/2 Find a quadratic polynomial each with the given numbers as the…
  31. 3, - 3 Find quadratic polynomial whose zeroes are :
  32. 2 + root 5/2 , 2 - root 5/2 Find quadratic polynomial whose zeroes are :…
  33. 3 + root 7 , 3 - root 7 Find quadratic polynomial whose zeroes are :…
  34. 1+2 root 3 , 1-2 root 3 Find quadratic polynomial whose zeroes are :…
  35. 2 - root 3/3 , 2 + root 3/3 Find quadratic polynomial whose zeroes are :…
  36. root 2 , 2 root 2 Find quadratic polynomial whose zeroes are :
  37. Find the quadratic polynomial whose zeroes are square of the zeroes of the…
  38. If α and β be the zeroes of the polynomial x^2 + 10x + 30, then find the…
  39. If 20 and be the zeroes of the polynomial x^2 + 4x + 3, find the quadratic…
  40. Find a quadratic polynomial whose zeroes are 1 and - 3. Verify the relation…
  41. Find the quadratic polynomial sum of whose zeroes in 8 and their product is…
Exercise 2.3
  1. Divide 2x^3 + 3x + 1 by x + 2 and find the quotient and the reminder. Is q(x) a…
  2. Divide 3x^3 + x^2 + 2x + 5 by 1 + 2x + x^2 and find the quotient and the…
  3. p(x) = x^3 - 3x^2 + 4x + 2 , g(x) = x - 1 Divide the polynomial p(x) by the…
  4. p(x) = 4x^3 - 3x^2 + 2x + 3 , g(x) = x + 4 Divide the polynomial p(x) by the…
  5. p(x) = 2x^4 + 3x^3 + 4x^2 + 19x + 45, g(x) = x - 2 Divide the polynomial p(x)…
  6. p(x) = x^4 + 2x^3 - 3x^2 + x - 1, g(x) = x - 2 Divide the polynomial p(x) by…
  7. p(x) = x^3 - 3x^2 - x + 3, g(x) = x^2 - 4x + 3 Divide the polynomial p(x) by…
  8. p(x) = x^6 + x^4 + x^3 + x^2 + 2x + 2, g(x) = x^3 + 1 Divide the polynomial…
  9. p(x) = x^6 + 3x^2 + 10 and g(x) = x^3 + 1 Divide the polynomial p(x) by the…
  10. p(x) = x^4 + 1, g(x) = x + 1 Divide the polynomial p(x) by the polynomial g(x)…
  11. By division process, find the value of k for which x - 1 is a factor of x^3 -…
  12. By division process, find the value of c for which 2x + 1 is a factor of 4x^4 -…
  13. p(x) = 2x^2 + 3x + 1, g(x) = x + 2 Apply Division Algorithm to find the…
  14. p(x) = x^3 - 3x^2 + 5x - 3, g(x) = x^2 - 2 Apply Division Algorithm to find the…
  15. p(x) = x^4 - 1 , g(x) = x + 1 Apply Division Algorithm to find the quotient…
  16. p(x) = x^3 - 3x^2 + 4x + 2 , g(x) = x - 1 Apply Division Algorithm to find the…
  17. p(x) = x^3 - 6x^2 + 11x - 6 , g(x) = x^2 - 5x + 6 Apply Division Algorithm to…
  18. p(x) = 6x^3 + 13x^2 + x - 2 , g(x) = 2x + 1 Apply Division Algorithm to find…
  19. x - 2, x^3 + 3x^3 - 12x + 4 Applying the Division Algorithm, check whether the…
  20. x^2 + 3x + 1,3x^4 + 5x^3 - 7x^2 + 2x + 2 Applying the Division Algorithm, check…
  21. x^2 - 3x + 4,2x^4 - 11x^3 + 29x^2 - 30x + 29 Applying the Division Algorithm,…
  22. x^2 - 4x + 3,x^3 - x^3 - 3x^4 - x + 3 Applying the Division Algorithm, check…
  23. t - 1, t^3 + t^2 - 2t + 1 Applying the Division Algorithm, check whether the…
  24. t^2 - 5t + 6,t^2 + 11t - 6 Applying the Division Algorithm, check whether the…
  25. Give examples of polynomials p(x), g(x), q(x) and r(x) satisfying the Division…
  26. x^3 - 6x^2 + 11x - 6;3 Find all the zeroes of the polynomial given below having…
  27. x^4 - 8x^3 + 23x^2 - 28x + 12;1,2 Find all the zeroes of the polynomial given…
  28. x^3 + 2x^2 - 2; - 2 Find all the zeroes of the polynomial given below having…
  29. x^3 + 5x^2 + 7x + 3; - 3 Find all the zeroes of the polynomial given below…
  30. x^4 - 6x^3 - 26x^2 + 138x - 35;2±√3 Find all the zeroes of the polynomial given…
  31. x^4 + x^3 - 34x^2 - 4x + 120;2, - 2. Find all the zeroes of the polynomial…
  32. 2x^4 + 7x^3 - 19x^2 - 14x + 30;√(2, - √2) Find all the zeroes of the polynomial…
  33. 2x^4 - 9x^3 + 5x^2 + 3x - 1;2±√3 Find all the zeroes of the polynomial given…
  34. 2x^3 - 4x - x^2 + 2;√2, - √2 Find all the zeroes of the polynomial given below…
  35. Verify that 3 ,-1 , - 1/3 are the zeroes of the cubic polynomial p(x) = 3x^2 -…
  36. x^3 - 4x^2 + 5x - 2;2, 1, 1 Verify that the numbers given alongside of the…
  37. x^3 - 6x^2 + 11x - 6 ;1, 2, 3 Verify that the numbers given alongside of the…
  38. x^3 + 2x^2 - x - 2; - 2 - 2, 1 Verify that the numbers given alongside of the…
  39. x^3 + 5x^2 + 7x + 3 ; - 3, 2 - 1, - 1 Verify that the numbers given alongside…
  40. Find a cubic polynomial having 1, 2, 3 as its zeroes.
  41. Find a cubic polynomial having - 3, - 2, 2 as its zeroes.
  42. Find a cubic polynomial with the sum of its zeroes are 0, - 7 and - 6…
  43. 2, - 7, - 14 Find a cubic polynomial with the sum of its zeroes, sum of the…
  44. -4 1/2 , 1/3 Find a cubic polynomial with the sum of its zeroes, sum of the…
  45. 5/7 , 1/7 , 1/7 Find a cubic polynomial with the sum of its zeroes, sum of the…
  46. 2/5 , 1/10 , 1/2 Find a cubic polynomial with the sum of its zeroes, sum of…

Exercise 2.1
Question 1.

Examine, seeing the graph of the polynomials given below, whether they are a linear or quadratic polynomial or neither linear nor quadratic polynomial:

(i) (ii)

(iii) (iv)

(v) (vi)

(vii) (viii)


Answer:

(i) In general, we know that for a linear polynomial ax + b, a≠0, the graph of y = ax + b is a straight line which intersects the x – axis at exactly one point.


And here, we can see that the graph of y = p(x) is a straight line and intersects the x – axis at exactly one point. Therefore, the given graph is of a Linear Polynomial.


(ii) Here, the graph of y = p(x) is a straight line and parallel to the x – axis . Therefore, the given graph is of a Linear Polynomial.


(iii) For any quadratic polynomial ax2 + bx + c, a ≠ 0, the graph of the corresponding equation y = a x2 + bx + c has one of the two shapes either open upwards like or open downwards like depending on whether a > 0 or a < 0. (These curves are called parabolas.)


Here, we can see that the shape of the graph is a parabola. Therefore, the given graph is of a Quadratic Polynomial.


(iv) For any quadratic polynomial ax2 + bx + c, a ≠ 0, the graph of the corresponding equation y = ax2 + bx + c has one of the two shapes either open upwards like or open downwards like depending on whether a > 0or a < 0. (These curves are called parabolas.)


Here, we can see that the shape of the graph is parabola. Therefore, the given graph is of a Quadratic Polynomial.


(v) The shape of the graph is neither a straight line nor a parabola. So, the graph is not of a linear polynomial nor a quadratic polynomial.


(vi) The given graph have a straight line but it doesn’t intersect at x – axis and the shape of the graph is also not a parabola. So, it is not a graph of a quadratic polynomial. Therefore, it is not a graph of linear polynomial or quadratic polynomial.


(vii) The shape of the graph is neither a straight line nor a parabola. So, the graph is not of a linear polynomial or a quadratic polynomial.


(viii) The shape of the graph is neither a straight line nor a parabola. So, the graph is not of a linear polynomial or a quadratic polynomial.



Question 2.

The graphs of y – p(x) are given in the figures below, where p(x) is a polynomial. Find the number of zeros in each case.

(i) (ii)

(iii) (iv)

(v) (vi)


Answer:

(i) Here, the graph of y = p(x) intersects the x – axis at two points. So, the number of zeroes is 2.


(ii) Here, the graph of y = p(x) intersects the x – axis at three points. So, the number of zeroes is 3.


(iii) Here, the graph of y = p(x) intersects the x – axis at one point only. So, the number of zeroes is 1.


(iv) Here, the graph of y = p(x) intersects the x – axis at exactly one point. So, the number of zeroes is 1.


(v) Here, the graph of y = p(x) intersects the x – axis at two points. So, the number of zeroes is 2.


(vi) Here, the graph of y = p(x) intersects the x – axis at exactly one point. So, the number of zeroes is 1.



Question 3.

The graphs of y = p(x) are given in the figures below, where p(x) is a polynomial Find the number of zeroes in each case.

(i) (ii)

(iii) (iv)

(v) (vi)


Answer:

(i) Here, the graph of y = p(x) intersect the x – axis at zero points. So, the number of zeroes is 0.


(ii) Here, the graph of y = p(x) intersects the x – axis at two points. So, the number of zeroes is 2.


(iii) Here, the graph of y = p(x) intersects the x – axis at four points. So, the number of zeroes is 4.


(iv) Here, the graph of y = p(x) does not intersects the x – axis. So, the number of zeroes is 0.


(v) Here, the graph of y = p(x) intersects the x – axis at two points. So, the number of zeroes is 2.


(vi) Here, the graph of y = p(x) intersects the x – axis at two points. So, the number of zeroes is 2.




Exercise 2.2
Question 1.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

x2 – 3


Answer:

Let f (x) = x2 – 3


Now, if we recall the identity


(a2 – b2) = (a – b)(a + b)


Using this identity, we can write


x2 – 3 = (x – √3) (x + √3)


So, the value of x2 – 3 is zero when x = √3 or x = – √3


Therefore, the zeroes of x2 – 3 are √3 and – √3.


Verification


Now,


Sum of zeroes = α + β = √3 + ( – √3) = 0 or



Product of zeroes = αβ = (√3)( – √3) = – 3 or



So, the relationship between the zeroes and the coefficients is verified.



Question 2.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

2x2 – 8x + 6


Answer:

Let f(x) = 2x2 – 8x + 6


By splitting the middle term, we get


f(x) = 2 x2 – (2 + 6)x + 6 [∵ – 8 = – (2 + 6) and 2×6 = 12]


= 2 x2 – 2x – 6x + 6


= 2x(x – 1) – 6(x – 1)


= (2x – 6) (x – 1)


On putting f(x) = 0, we get


(2x – 6) (x – 1) = 0


⇒2x – 6 = 0 or x – 1 = 0


⇒x = 3 or x = 1


Thus, the zeroes of the given polynomial 2 x2 – 8x + 6 are 1 and 3


Verification


Sum of zeroes = α + β = 3 + 1 = 4 or



Product of zeroes = αβ = (3)(1) = 3 or



So, the relationship between the zeroes and the coefficients is verified.



Question 3.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

x2 – 2x – 8


Answer:

Let f(x) = x2 – 2x – 8


By splitting the middle term, we get


f(x) = x2 – 4x + 2x – 8 [∵ – 2 = 2 – 4 and 2×4 = 8]


= x(x – 4) + 2(x – 4)


= (x + 2) (x – 4)


On putting f(x) = 0, we get


(x + 2) (x – 4) = 0


⇒ x + 2 = 0 or x – 4 = 0


⇒x = – 2 or x = 4


Thus, the zeroes of the given polynomial x2 – 2x – 8 are – 2 and 4


Verification


Sum of zeroes = α + β = – 2 + 4 = 2 or



Product of zeroes = αβ = ( – 2)(4) = – 8 or



So, the relationship between the zeroes and the coefficients is verified.



Question 4.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

3x2 + 5x – 2


Answer:

Let f(x) = 3x2 + 5x – 2


By splitting the middle term, we get


f(x) = 3x2 + (6 – 1)x – 2 [∵ 5 = 6 – 1 and 2×3 = 6]


= 3x2 + 6x – x – 2


= 3x(x + 2) – 1(x + 2)


= (3x – 1) (x + 2)


On putting f(x) = 0 , we get


(3x – 1) (x + 2) = 0


⇒ 3x – 1 = 0 or x + 2 = 0


or x = – 2


Thus, the zeroes of the given polynomial 3x2 + 5x – 2 are – 2 and


Verification


Sum of zeroes or



Product of zeroes or


=


So, the relationship between the zeroes and the coefficients is verified.



Question 5.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

3x2 – x – 4


Answer:

Let f(x) = 3x2 – x – 4


By splitting the middle term, we get


f(x) = 3x2 – (4 – 3)x – 4 [∵ – 1 = 3 – 4 and 4×3 = 12]


= 3x2 + 3x – 4x – 4


= 3x(x + 1) – 4(x + 1)


= (3x – 4) (x + 1)


On putting f(x) = 0, we get


(3x – 4) (x + 1) = 0


⇒ 3x – 4 = 0 or x + 1 = 0


or x = – 1


Thus, the zeroes of the given polynomial 3x2 – x – 4 are – 1 and


Verification


Sum of zeroes or



Product of zeroes or



So, the relationship between the zeroes and the coefficients is verified.



Question 6.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

x2 + 7x + 10


Answer:

Let f(x) = x2 + 7x + 10


By splitting the middle term, we get


f(x) = x2 + 5x + 2x + 10 [∵ 7 = 2 + 5 and 2×5 = 10]


= x(x + 5) + 2(x + 5)


= (x + 2) (x + 5)


On putting f(x) = 0 , we get


(x + 2) (x + 5) = 0


⇒ x + 2 = 0 or x + 5 = 0


⇒x = – 2 or x = – 5


Thus, the zeroes of the given polynomial x2 + 7x + 10 are – 2 and – 5


Verification


Sum of zeroes = α + β = – 2 + ( – 5) = – 7 or



Product of zeroes = αβ = ( – 2)( – 5) = 10 or



So, the relationship between the zeroes and the coefficients is verified.



Question 7.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

t2 – 15


Answer:

Let f(x) = t2 – 15


Now, if we recall the identity


(a2 – b2) = (a – b)(a + b)


Using this identity, we can write


t2 – 15 = (t – √15) (x + √15)


So, the value of t2– 15 is zero when t = √15 or t = – √15


Therefore, the zeroes of t2– 15 are √15 and – √15.


Verification


Now,


Sum of zeroes = α + β = √15 + ( – √15) = 0 or



Product of zeroes = αβ = (√15)( – √15) = – 15 or



So, the relationship between the zeroes and the coefficients is verified.



Question 8.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

4 s2 – 4s + 1


Answer:

Let f(x) = 4 s2 – 4s + 1


By splitting the middle term, we get


f(x) = 4 s2 – (2 – 2)s + 1 [∵ – 4 = – (2 + 2) and 2×2 = 4]


= 4 s2 – 2s – 2s + 1


= 2s(2s – 1) – 1(2s – 1)


= (2s – 1) (2s – 1)


On putting f(x) = 0 , we get


(2s – 1) (2s – 1) = 0


⇒ 2s – 1 = 0 or 2s – 1 = 0


or


Thus, the zeroes of the given polynomial 4 s2 – 4s + 1 are and


Verification


Sum of zeroes or



Product of zeroes or



So, the relationship between the zeroes and the coefficients is verified.



Question 9.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

8x2– 22x – 21


Answer:

Let f(x) = 8x2 – 22x – 21


By splitting the middle term, we get


f(x) = 8x2 – 28x + 6x – 21


= 4x(2x – 7) + 3(2x – 7)


= (4x + 3) (2x – 7)


On putting f(x) = 0 , we get


(4x + 3) (2x – 7) = 0


⇒ 4x + 3 = 0 or 2x – 7 = 0


or


Thus, the zeroes of the given polynomial 8x2 – 22x – 21 are and


Verification


Sum of zeroes or



The product of zeroes or



So, the relationship between the zeroes and the coefficients is verified.



Question 10.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

2x2 – 7x


Answer:

Let f(x) = 2 x2 – 7x


In this the constant term is zero.


f(x) = 2 x2 – 7x


= x(2x – 7)


On putting f(x) = 0 , we get


x(2x – 7) = 0


⇒ 2x – 7 = 0 or x = 0


or x = 0


Thus, the zeroes of the given polynomial 2x2 – 7x are 0 and


Verification


Sum of zeroes or



Product of zeroes or



So, the relationship between the zeroes and the coefficients is verified.



Question 11.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

10x2 + 3x – 1


Answer:

Let f(x) = 10x2 + 3x – 1


By splitting the middle term, we get


f(x) = 10x2 – 2x + 5x – 1


= 2x(5x – 1) + 1(5x – 1)


= (2x + 1) (5x – 1)


On putting f(x) = 0, we get


(2x + 1) (5x – 1) = 0


⇒ 2x + 1 = 0 or 5x – 1 = 0


= or =


Thus, the zeroes of the given polynomial10x2 + 3x – 1 are and


Verification


Sum of zeroes



Product of zeroes or



So, the relationship between the zeroes and the coefficients is verified.



Question 12.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

px2 + (2q – p2)x – 2pq, p≠0


Answer:

Let f(x) = px2 + (2q – p2)x – 2pq


f(x) = px2 + 2qx – p2 x – 2pq


= x(px + 2q) – p(px + 2q)


= (x – p) (px + 2q)


On putting f(x) = 0, we get


(x – p) (px + 2q) = 0


⇒ x – p = 0 or px + 2q = 0


⇒x = p or =


Thus, the zeroes of the given polynomial px2 + (2q – p2)x – 2pq are p and


Verification


Sum of zeroes



Product of zeroes or



So, the relationship between the zeroes and the coefficients is verified.



Question 13.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

x2 – (2a + b)x + 2ab


Answer:

Let f(x) = x2 – (2a + b)x + 2ab


f(x) = x2 – 2ax – bx + 2ab


= x(x – 2a) – b(x – 2a)


= (x – 2a) (x – b)


On putting f(x) = 0 , we get


(x – 2a) (x – b) = 0


⇒ x – 2a = 0 or x – b = 0


⇒x = 2a or x = b


Thus, the zeroes of the given polynomial x2 – (2a + b)x + 2ab are 2a and b


Verification


Sum of zeroes = α + β = 2a + b or



Product of zeroes = αβ = 2a × b = 2ab or



So, the relationship between the zeroes and the coefficients is verified.



Question 14.

Find the zeroes of the following quadratic polynomials and verify the relationship between the zeroes and the coefficients:

r2s2x2 + 6rstx + 9t2


Answer:

Let f(x) = r2s2x2 + 6rstx + 9t2


Now, if we recall the identity


(a + b)2 = a2 + b2 + 2ab


Using this identity, we can write


r2s2x2 + 6rstx + 9t2 = (rsx + 3t)2


On putting f(x) = 0 , we get


(rsx + 3t)2 = 0



Thus, the zeroes of the given polynomial r2s2x2 + 6rstx + 9t2 are and


Verification


Sum of zeroes or



or



So, the relationship between the zeroes and the coefficients is verified.



Question 15.

Find the zeroes of the quadratic polynomial 5x2 – 8x – 4 and verify the relationship between the zeroes and the coefficients of the polynomial.


Answer:

Let f(x) = 5x2 – 8x – 4


By splitting the middle term, we get


f(x) = 5x2 – 10x + 2x – 4


= 5x(x – 2) + 2(x – 2)


= (5x + 2) (x – 2)


On putting f(x) = 0 we get


(5x + 2) (x – 2) = 0


⇒ 5x + 2 = 0 or x – 2 = 0


or x = 2


Thus, the zeroes of the given polynomial5x2 – 8x – 4 are and 2


Verification


Sum of zeroes or



Product of zeroes or



So, the relationship between the zeroes and the coefficients is verified.



Question 16.

Find the zeroes of the quadratic polynomial 4 x2 – 4x – 3 and verify the relationship between the zeroes and the coefficients of the polynomial.


Answer:

Let f(x) = 4 x2 – 4x – 3


By splitting the middle term, we get


f(x) = 4 x2 – 6x + 2x – 3


= 2x(2x – 3) + 1(2x – 3)


= (2x + 1) (2x – 3)


On putting f(x) = 0, we get


(2x + 1) (2x – 3) = 0


⇒ 2x + 1 = 0 or 2x – 3 = 0


or


Thus, the zeroes of the given polynomial4x2 – 4x – 3 are and


Verification


Sum of zeroes or



Product of zeroes or



So, the relationship between the zeroes and the coefficients is verified.



Question 17.

Find the zeroes of the quadratic polynomial √3 x2 – 8x + 4√3 .


Answer:

Let f(x) = √3 x2 – 8x + 4√3


By splitting the middle term, we get


(x) = √3 x2 – 6x – 2x + 4√3


= √3 x(x – 2√3) – 2(x – 2√3)


= (√3 x – 2) (x – 2√3)


On putting f (x) = 0, we get


(√3 x – 2) (x – 2√3) = 0


⇒ √3 x – 2 = 0 or x – 2√(3 = 0)


or


Thus, the zeroes of the given polynomial√3 x2 – 8x + 4√3 are and 2


Verification


Sum of zeroes or



Product of zeroes or



So, the relationship between the zeroes and the coefficients is verified.



Question 18.

If α and β be the zeroes of the polynomial 2x2 + 3x – 6, find the values of

(i) α2 + β2 (ii) α2 + β2 + αβ

(iii) α2β + αβ2 (iv)

(v) (vi) α – β

(vii) α3 + β3 (viii)


Answer:

Let the quadratic polynomial be 2 x2 + 3x – 6, and its zeroes are α and β.


We have



Here, a = 2 , b = 3 and c = – 6


….(1)


….(2)


(i) α2 + β2


We have to find the value of α2 + β2


Now, if we recall the identity


(a + b)2 = a2 + b2 + 2ab


Using the identity, we get



(α + β)2 = α2 + β2 + 2αβ


{from eqn (1) & (2)}




(ii) α2 + β2 + αβ


{ from part (i)}


and, we have αβ = – 3


So,


=


=


(iii) α2β + α β2


Firstly, take common, we get


αβ(α + β)


and we already know the value of and .


So, α2β + α β2 = αβ(α + β)


{from eqn (1) and (2)}



(iv)


Let’s take the LCM first then we get,





(v)


Let’s take the LCM first then we get,



{from part(i) and eqn (2)}



(vi)


Now, recall the identity


(a – b)2 = a2 + b2 – 2ab


Using the identity , we get


(α – β)2 = α2 + β2 – 2 αβ


{from part(i) and eqn (2)}



= =



(vii)


Now, recall the identity


(a + b)3 = a3 + b3 + 3a2 b + 3ab2


Using the identity, we get


⇒(α + β)3 = α3 + β3 + 3α2 β + 3αβ2






(viii)


Let’s take the LCM first then we get,



{from part(vii) and eqn (2)}




Question 19.

If α and β be the zeroes of the polynomial ax2 + bx + c, find the values of

(i)

(ii)

(ii)


Answer:

Let the quadratic poynomial be ax2 + bx + c , and its zeroes be α and β.


We have


α + β = and α β =


(i)


We have to find the value of


Now, if we recall the identity


(a + b)2 = a2 + b2 + 2ab


Using the identity, we get


{from eqn (1) & (2)}





(ii)


Let’s take the LCM first then we get,



{}



(iii)


Now, recall the identity


(a + b)3 = a3 + b3 + 3a2 b + 3ab2


Using the identity, we get


⇒(α + β)3 = α3 + β3 + 3α2 β + 3αβ2







Question 20.

If α, β are the zeroes of the quadratic polynomial x2 + kx = 12, such that α – β = 1, find the value of k.


Answer:

The given quadratic polynomial is x2 + kx = 12 and = 1


If we rearrange the polynomial then we get


p(x) = x2 + kx – 12


We have,


and


So,


…(1)


…(2)


Now, if we recall the identities


(a + b)2 = a2 + b2 + 2ab


Using the identity, we get



(α + β)2 = α2 + β2 + 2 αβ


( – k)2 = α2 + β2 + 2( – 12)


⇒ α2 + β2 = k2 + 24 …(3)


Again, using the identity


(a – b)2 = a2 + b2 – 2ab


Using the identity, we get
(α – β)2 = α2 + β2 – 2 αβ


(1)2 = α2 + β2 – 2( – 12) {∵ (α – β) = 1}


⇒ α2 + β2 = 1 – 24


⇒ α2 + β2 = – 23 …(4)


From eqn (3) and (4), we get


k2 + 24 = – 23


⇒ k2 = – 23 – 24


⇒ k2 = – 47


Now the square can never be negative, so the value of k is imaginary.



Question 21.

If the sum of squares of the zeroes of the quadratic polynomial x2 – 8x + k is 40, find k.


Answer:

Given : p(x) = x2 – 8x + k


α2 + β2 = 40


We have,



and


So,


…(1)


…(2)


Now, if we recall the identities


(a + b)2 = a2 + b2 + 2ab


Using the identity, we get


(α + β)2 = α2 + β2 + 2 αβ


(8)2 = + 2(k)


⇒2k = 64 – 40


= = 12



Question 22.

If one zero of the polynomial (α2 + 9) x2 + 13x + 6α is reciprocal of the other, find the value of a.


Answer:

Let one zero of the given polynomial is


According to the given condition,


The other zero of the polynomial is


We have,


Product of zeroes,



⇒ α2 – 6α + 9 = 0


⇒ α2 – 3α – 3α + 9 = 0


⇒ α(α – 3) – 3(α – 3) = 0


⇒(α – 3)(α – 3) = 0


⇒(α – 3) = 0 & (α – 3) = 0


⇒ α = 3, 3



Question 23.

If the product of zeroes of the polynomial α2 – 6x – 6 is 4, find the value of a.


Answer:

Given Product of zeroes, α β = 4


p(x) = α x2 – 6x – 6


to find: value of α


We know,


Product of zeroes ,





Question 24.

If (x + a) is a factor 2x2 + 2ax + 5x + 10, find a.


Answer:

Given x + a is a factor of


So,g(x) = x + a


x + a = 0


⇒x = – a


Putting the value x = – a in the given polynomial, we get


2( – a)2 + 2a( – a) + 5( – a) + 10 = 0


2a2 – 2a2 – 5a + 10 = 0


– 5a + 10 = 0



a = 2



Question 25.

Find a quadratic polynomial each with the given numbers as the sum and product of its zeroes respectively:

1,1


Answer:

Given: Sum of zeroes = α + β = 1


Product of zeroes = αβ = 1


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


= x2 – (1)x + 1


= x2 – x + 1



Question 26.

Find a quadratic polynomial each with the given numbers as the sum and product of its zeroes respectively:

0,3


Answer:

Given: Sum of zeroes = α + β = 0


Product of zeroes = αβ = 3


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


= x2 – (0)x + 3


= x2 + 3



Question 27.

Find a quadratic polynomial each with the given numbers as the sum and product of its zeroes respectively:



Answer:

Given: Sum of zeroes = α + β = 1/4


Product of zeroes = αβ = – 1


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


=


=


=


We can consider 4x2 – x – 4 as required quadratic polynomial because it will also satisfy the given conditions.



Question 28.

Find a quadratic polynomial each with the given numbers as the sum and product of its zeroes respectively:

4,1


Answer:

Given: Sum of zeroes = = 4


Product of zeroes = = 1


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


= x2 – (4)x + 1


= x2 – 4x + 1



Question 29.

Find a quadratic polynomial each with the given numbers as the sum and product of its zeroes respectively:



Answer:

Given: Sum of zeroes


Product of zeroes = αβ = – 1


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


=


=


=


We can consider 3x2 – 10x – 3 as required quadratic polynomial because it will also satisfy the given conditions.



Question 30.

Find a quadratic polynomial each with the given numbers as the sum and product of its zeroes respectively:



Answer:

Given: Sum of zeroes


Product of zeroes


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


=


=


=


We can consider 2x2 + x – 1 as required quadratic polynomial because it will also satisfy the given conditions.



Question 31.

Find quadratic polynomial whose zeroes are :

3, – 3


Answer:

Let the zeroes of the quadratic polynomial be


α = 3 , β = – 3


Then, α + β = 3 + ( – 3) = 0


αβ = 3 × ( – 3) = – 9


Sum of zeroes = α + β = 0


Product of zeroes = αβ = – 9


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


= x2 – (0)x + ( – 9)


= x2 – 9



Question 32.

Find quadratic polynomial whose zeroes are :



Answer:

Let the zeroes of the quadratic polynomial be



Then,



Sum of zeroes = α + β = 2


Product of zeroes = =


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


=


=


=


We can consider 4x2 – 8x – 1 as required quadratic polynomial because it will also satisfy the given conditions.



Question 33.

Find quadratic polynomial whose zeroes are :



Answer:

Let the zeroes of the quadratic polynomial be


α = 3 + √7, β = 3 – √7


Then, α + β = 3 + √7 + 3 – √7 = 6


αβ = (3 + √(7)) × (3 – √7) = 9 – 7 = 2


Sum of zeroes = α + β = 6


Product of zeroes = αβ = 2


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


= x2 – (6)x + 2


= x2 – 6x + 2



Question 34.

Find quadratic polynomial whose zeroes are :



Answer:

Let the zeroes of the quadratic polynomial be


α = 1 + 2√3, β = 1 – 2√3


Then, α + β = 1 + 2√3 + 1 – 2√3 = 2


αβ = (1 + 2√3) × (1 – 2√3) = 1 – 12 = – 11


Sum of zeroes = α + β = 2


Product of zeroes = αβ = – 11


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


= x2 – (2)x + ( – 11)


= x2 – 2x – 11



Question 35.

Find quadratic polynomial whose zeroes are :



Answer:

Let the zeroes of the quadratic polynomial be



Then,



Sum of zeroes


Product of zeroes


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


=


=


=


We can consider 9x2 – 12x + 1 as required quadratic polynomial because it will also satisfy the given conditions.



Question 36.

Find quadratic polynomial whose zeroes are :



Answer:

Let the zeroes of the quadratic polynomial be


α = √2, β = 2√2


Then, α + β = √2 + 2√2 = √2 (1 + 2) = 3√2


αβ = √2× 2√2 = 4


Sum of zeroes = α + β = 3√2


Product of zeroes = αβ = 4


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


= x2 – (3√2)x + 4


= x2 – 3√2 x + 4



Question 37.

Find the quadratic polynomial whose zeroes are square of the zeroes of the polynomial x2 – x – 1.


Answer:

et the zeroes of the polynomial x2 – x – 1 be α and β


We have,



and


So,




Now, according to the given condition,


α2 β2 = ( – 1)2 = 1


& (α + β)2 = α2 + β2 + 2 α β


α2 + β2 = (α + β)2 – 2αβ


α2 + β2 = (1)2 – 2( – 1)


α2 + β2 = 3


So, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


= x2 – (3)x + 1


= x2 – 3x + 1



Question 38.

If α and β be the zeroes of the polynomial x2 + 10x + 30, then find the quadratic polynomial whose zeroes are α + 2β and 2α + β.


Answer:

Given : p(x) = x2 + 10x + 30


So, Sum of zeroes …(1)


Product of zeroes …(2)


Now,


Let the zeroes of the quadratic polynomial be


α^' = α + 2β , β' = 2α + β


Then, α’ + β’ = α + 2β + 2α + β = 3α + 3β = 3(α + β)


α'β’ = (α + 2β) ×(2α + β) = 2α2 + 2β2 + 5αβ


Sum of zeroes = 3(α + β)


Product of zeroes = 2α2 + 2β2 + 5αβ


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


= x2 – (3(α + β))x + 2α2 + 2β2 + 5αβ


= x2 – 3( – 10)x + 2 (α2 + β2) + 5(30) {from eqn (1) & (2)}


= x2 + 30x + 2(α2 + β2 + 2αβ – 2αβ) + 150


= x2 + 30x + 2 (α + β)2 – 4αβ + 150


= x2 + 30x + 2( – 10)2 – 4(30) + 150


= x2 + 30x + 200 – 120 + 150


= x2 + 30x + 230


So, the required quadratic polynomial is x2 + 30x + 230



Question 39.

If α and β be the zeroes of the polynomial x2 + 4x + 3, find the quadratic polynomial whose zeroes are and .


Answer:

Given : p(x) = x2 + 4x + 3


So, Sum of zeroes …(1)


Product of zeroes …(2)


Now,


Let the zeroes of the quadratic polynomial be



Then,



Sum of zeroes


Product of zeroes


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


= +


= {from eqn (1) & (2)}


= +


=


So, the required quadratic polynomial is 3x2 – 16x + 16



Question 40.

Find a quadratic polynomial whose zeroes are 1 and – 3. Verify the relation between the coefficients and zeroes of the polynomial.


Answer:

Let the zeroes of the quadratic polynomial be


α = 1 , β = – 3


Then, α + β = 1 + ( – 3) = – 2


αβ = 1 × ( – 3) = – 3


Sum of zeroes = α + β = – 2


Product of zeroes = αβ = – 3


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


= x2 – ( – 2)x + ( – 3)


= x2 + 2x – 3


Verification


Sum of zeroes = α + β = 1 + ( – 3) = – 2 or



Product of zeroes = αβ = (1)( – 3) = – 3 or



So, the relationship between the zeroes and the coefficients is verified.



Question 41.

Find the quadratic polynomial sum of whose zeroes in 8 and their product is 12. Hence find the zeroes of the polynomial.


Answer:

Given: Sum of zeroes = α + β = 8


Product of zeroes = αβ = 12


Then, the quadratic polynomial


= x2 – (sum of zeroes)x + product of zeroes


= x2 – (8)x + 12


= x2 – 8x + 12


Now, we have


and


So,






Exercise 2.3
Question 1.

Divide 2x3 + 3x + 1 by x + 2 and find the quotient and the reminder. Is q(x) a factor of 2x3 + 3x + 1 ?


Answer:

Here, dividend and divisor both are in the standard form.


Now, on dividing p(x) by g(x) we get the following division process



Quotient = 2x2 – 4x + 11


Remainder = – 21


No, 2x2 – 4x + 11 is not a factor of 2x3 + 3x + 1 because remainder ≠ 0



Question 2.

Divide 3x3 + x2 + 2x + 5 by 1 + 2x + x2 and find the quotient and the remainder. Is 1 + 2x + x2 a factor of 3x3 + x2 + 2x + 5


Answer:

Dividend = 3x3 + x2 + 2x + 5


Divisor = x2 + 2x + 1


Now, dividend and divisor both are in the standard form.


Now, on dividing p(x) by g(x) we get the following division process



Quotient = 3x – 5


Remainder = 9x + 10


No, x2 + 2x + 1 is not a factor of 3x3 + x2 + 2x + 5 because remainder ≠ 0



Question 3.

Divide the polynomial p(x) by the polynomial g(x) and find the quotient q(x) and remainder r(x) in each case :

p(x) = x3 – 3x2 + 4x + 2 , g(x) = x – 1


Answer:

p(x) = x3 – 3x2 + 4x + 2,g(x) = x – 1


Dividend = x3 – 3x2 + 4x + 2


Divisor = x – 1


Here, dividend and divisor both are in the standard form.


Now, on dividing p(x) by g(x) we get the following division process



Quotient = x2 – 2x + 2


Remainder = 4



Question 4.

Divide the polynomial p(x) by the polynomial g(x) and find the quotient q(x) and remainder r(x) in each case :

p(x) = 4x3 – 3x2 + 2x + 3 , g(x) = x + 4


Answer:

p(x) = 4x3 – 3x2 + 2x + 3,g(x) = x + 4


Dividend = 4x3 – 3x2 + 2x + 3


Divisor = x + 4


Here, dividend and divisor both are in the standard form.


Now, on dividing by we get the following division process



Quotient = 4x2 – 13x + 54


Remainder = – 213



Question 5.

Divide the polynomial p(x) by the polynomial g(x) and find the quotient q(x) and remainder r(x) in each case :

p(x) = 2x4 + 3x3 + 4x2 + 19x + 45, g(x) = x – 2


Answer:

p(x) = 2x4 + 3x3 + 4x2 + 19x + 45, g(x) = x – 2


Dividend = 2x4 + 3x3 + 4x2 + 19x + 45


Divisor = x – 2


Here, dividend and divisor both are in the standard form.


Now, on dividing p(x) by g(x) we get the following division process we get,



q(x) = 2x3+7x2+18x+55


r(x) = 155



Question 6.

Divide the polynomial p(x) by the polynomial g(x) and find the quotient q(x) and remainder r(x) in each case :

p(x) = x4 + 2x3 – 3x2 + x – 1, g(x) = x – 2


Answer:

p(x) = x4 + 2x3 – 3x2 + x – 1, g(x) = x – 2


Dividend = x4 + 2x3 – 3x2 + x – 1


Divisor = x – 2


Here, dividend and divisor both are in the standard form.


Now, on dividing p(x) by g(x) we get the following division process we get,



q(x) = x3+4x2+5x+11


r(x) = 21



Question 7.

Divide the polynomial p(x) by the polynomial g(x) and find the quotient q(x) and remainder r(x) in each case :

p(x) = x3 – 3x2– x + 3, g(x) = x2 – 4x + 3


Answer:

p(x) = x3 – 3x2– x + 3, g(x) = x2 – 4x + 3


Dividend = x3 – 3x2– x + 3


Divisor = x2 – 4x + 3


Here, dividend and divisor both are in the standard form.


Now, on dividing p(x) by g(x) we get the following division process we get,



q(x)= x + 1


r(x) = 0



Question 8.

Divide the polynomial p(x) by the polynomial g(x) and find the quotient q(x) and remainder r(x) in each case :

p(x) = x6 + x4 + x3 + x2 + 2x + 2, g(x) = x3 + 1


Answer:

p(x) = x6 + x4 + x3 + x2 + 2x + 2, g(x) = x3 + 1


Dividend = x6 + x4 + x3 + x2 + 2x + 2


Divisor = x3 + 1


Here, dividend and divisor both are in the standard form.


Now, on dividing p(x) by g(x) we get the following division process we get,



q(x) = x3 + x


r(x) = x2 + x + 2



Question 9.

Divide the polynomial p(x) by the polynomial g(x) and find the quotient q(x) and remainder r(x) in each case :

p(x) = x6 + 3x2 + 10 and g(x) = x3 + 1


Answer:

p(x) = x6 + 3x2 + 10 , g(x) = x3 + 1


Dividend = x6 + 3x2 + 10


Divisor = x3 + 1


Here, dividend and divisor both are in the standard form.


Now, on dividing p(x) by g(x) we get the following division process we get,



q(x) = x3 – 1


r(x) = 3x2 + 11



Question 10.

Divide the polynomial p(x) by the polynomial g(x) and find the quotient q(x) and remainder r(x) in each case :

p(x) = x4 + 1, g(x) = x + 1


Answer:

p(x) = x4 + 1, g(x) = x + 1


Dividend = x4 + 1,


Divisor = x + 1



q(x) = x3 – x2 + x – 1


r(x) = 0



Question 11.

By division process, find the value of k for which x – 1 is a factor of x3 – 6x2 + 11x + k.


Answer:

On dividing x3 – 6x2 + 11x + k by x – 1 we get,



Since x – 1 is a factor of x3 – 6x2 + 11x + k,


This means x – 1 divides the given polynomial completely.


→ 6 x + k = 0


→ k = – 6x



Question 12.

By division process, find the value of c for which 2x + 1 is a factor of 4x4 – 3x2 + 3x + c.


Answer:

On dividing 4x4 – 3x2 + 3x + c by 2x + 1 we get,



Since 2x + 1 is a factor of 4x4 – 3x2 + 3x + c,


This means 2x + 1 divides the given polynomial completely,


→ 4x + c = o


→ c = – 4x



Question 13.

Apply Division Algorithm to find the quotient q(x) and remainder r(x) on dividing p(x) by g(x) as given below:

p(x) = 2x2 + 3x + 1, g(x) = x + 2


Answer:

p(x) = 2x2 + 3x + 1, g(x) = x + 2


Dividend = 2x2 + 3x + 1,


Divisor = x + 2


Apply the division algorithm we get,



q(x) = 2x – 1


r(x) = 3



Question 14.

Apply Division Algorithm to find the quotient q(x) and remainder r(x) on dividing p(x) by g(x) as given below:

p(x) = x3 – 3x2 + 5x – 3, g(x) = x2 – 2


Answer:

p(x) = x3 – 3x2 + 5x – 3, g(x) = x2 – 2


Dividend = x3 – 3x2 + 5x – 3,


Divisor = x2 – 2


On applying division algorithm, we get,



q(x) = x – 3


r(x) = 7x – 9



Question 15.

Apply Division Algorithm to find the quotient q(x) and remainder r(x) on dividing p(x) by g(x) as given below:

p(x) = x4 – 1 , g(x) = x + 1


Answer:

p(x) = x4 – 1,g(x) = x + 1


Dividend = x4 – 1


Divisor = x + 1


Here, dividend and divisor both are in the standard form.


Now, on dividing p(x) by g(x) we get the following division process



Quotient = x3 – x2 + x – 1


Remainder = 0



Question 16.

Apply Division Algorithm to find the quotient q(x) and remainder r(x) on dividing p(x) by g(x) as given below:

p(x) = x3 – 3x2 + 4x + 2 , g(x) = x – 1


Answer:

p(x) = x3 – 3x2 + 4x + 2,g(x) = x – 1


Dividend = x3 – 3x2 + 4x + 2


Divisor = x – 1


Here, dividend and divisor both are in the standard form.


Now, on dividing p(x) by g(x) we get the following division process



Quotient = x – 5


Remainder = 13x + 7



Question 17.

Apply Division Algorithm to find the quotient q(x) and remainder r(x) on dividing p(x) by g(x) as given below:

p(x) = x3 – 6x2 + 11x – 6 , g(x) = x2 – 5x + 6


Answer:

p(x) = x3 – 6x2 + 11x – 6,g(x) = x2 – 5x + 6


Dividend = x3 – 6x2 + 11x – 6


Divisor = x2 – 5x + 6


Here, dividend and divisor both are in the standard form.


Now, on dividing p(x) by g(x) we get the following division process



Quotient = x – 1


Remainder = 6x



Question 18.

Apply Division Algorithm to find the quotient q(x) and remainder r(x) on dividing p(x) by g(x) as given below:

p(x) = 6x3 + 13x2 + x – 2 , g(x) = 2x + 1


Answer:

p(x) = 6x3 + 13x2 + x – 2,g(x) = 2x + 1


Dividend = 6x3 + 13x2 + x – 2


Divisor = 2x + 1


Here, dividend and divisor both are in the standard form.


Now, on dividing p(x) by g(x) we get the following division process



Quotient = 3x2 + 5x – 2


Remainder = 0



Question 19.

Applying the Division Algorithm, check whether the first polynomial is a factor of the second polynomial:

x – 2, x3 + 3x3 – 12x + 4


Answer:

Let us divide x3 + 3x2 – 12x + 4 by x – 2


The division process is



Here, the remainder is 0, therefore x – 2 is a factor of x3 + 3x2 – 12x + 4



Question 20.

Applying the Division Algorithm, check whether the first polynomial is a factor of the second polynomial:

x2 + 3x + 1,3x4 + 5x3 – 7x2 + 2x + 2


Answer:

Let us divide 3x4 + 5x3 – 7x2 + 2x + 2 by x2 + 3x + 1


The division process is



Here, the remainder is 0, therefore x2 + 3x + 1 is a factor of 3x4 + 5x3 – 7x2 + 2x + 2



Question 21.

Applying the Division Algorithm, check whether the first polynomial is a factor of the second polynomial:

x2 – 3x + 4,2x4 – 11x3 + 29x2 – 30x + 29


Answer:

Let us divide 2x4 – 11x3 + 29x2 – 30x + 29 by x2 – 3x + 4


The division process is



Here, the remainder is 58x – 115 , therefore x2 – 3x + 4 is not a factor of 2x4 – 11x3 + 29x2 – 30x + 29



Question 22.

Applying the Division Algorithm, check whether the first polynomial is a factor of the second polynomial:

x2 – 4x + 3,x3 – x3 – 3x4 – x + 3


Answer:

Let us divide x3 – 3x2 – x + 3 by x2 – 4x + 3


The division process is



Here, the remainder is 0, therefore x2 – 4x + 3 is a factor of x3 – 3x2 – x + 3



Question 23.

Applying the Division Algorithm, check whether the first polynomial is a factor of the second polynomial:

t – 1, t3 + t2 – 2t + 1


Answer:

Let us divide t3 + t2 – 2t + 1 by t – 1


The division process is



Here, the remainder is 1, therefore t – 1 is not a factor of t3 + t2 – 2t + 1



Question 24.

Applying the Division Algorithm, check whether the first polynomial is a factor of the second polynomial:

t2 – 5t + 6,t2 + 11t – 6


Answer:

Let us divide t2 + 11t – 6 by t2 – 5t + 6


The division process is



Here, the remainder is 16t – 12,


Therefore, t2 – 5t + 6 is not a factor of t2 + 11t – 6



Question 25.

Give examples of polynomials p(x), g(x), q(x) and r(x) satisfying the Division Algorithm

p(x) = g(x).q(x) + r(x),deg r(x)<deg g(x)

And also satisfying

(i) deg p(x) = deg q(x) + 1

(ii)deg q(x) = 1

(iii) deg q(x) = deg r(x) + 1


Answer:

(i)Let p(x) = 12x2 + 8x + 25, g(x) = 4,


q(x) = 3x2 + 2x + 6 , r(x) = 0


Here, degree p(x) = degree q(x) = 2


Now, g(x).q(x) + r(x) = (3x2 + 2x + 6)×4 + 1


= 12x2 + 8x + 24 + 1


= 12x2 + 8x + 25


(ii) Let p(x) = t3 + t2 – 2t, g(x) = t2 + 2t,


q(x) = t – 1 , r(x) = 0


Here, degree q(x) = 1


Now, g(x).q(x) + r(x) = (t2 + 2t)×(t – 1) + 0


= t3 – t2 + 2t2 – 2t


= t3 + t2 – 2t


(iii) Let p(x) = x3 + x2 + x + 1 , g(x) = x2 – 1,


q(x) = x + 1 , r(x) = 2x + 2


Here, degree q(x) = degree r(x) + 1 = 1


Now, g(x).q(x) + r(x) = (x2 – 1)×(x + 1) + 2x + 2


= x3 + x2 – x – 1 + 2x + 2


= x3 + x2 + x + 1



Question 26.

Find all the zeroes of the polynomial given below having given numbers as its zeroes.

x3 – 6x2 + 11x – 6;3


Answer:

Given zeroes is 3


So, (x – 3) is the factor of x3 – 6x2 + 11x – 6


Let us divide x3 – 6x2 + 11x – 6 by x – 3


The division process is



Here, quotient = x2 – 3x + 2


= x2 – 2x – x + 2


= x(x – 2) – 1(x – 2)


= (x – 1)(x – 2)


So, the zeroes are 1 and 2


Hence, all the zeroes of the given polynomial are 1, 2 and 3.



Question 27.

Find all the zeroes of the polynomial given below having given numbers as its zeroes.

x4 – 8x3 + 23x2 – 28x + 12;1,2


Answer:

Given zeroes are 1 and 2


So, (x – 1)and (x – 2) are the factors of x4 – 8x3 + 23x2 – 28x + 12


⟹ (x – 1)(x – 2) = x2 – 3x + 2 is a factor of given polynomial.


Consequently, x2 – 3x + 2 is also a factor of the given polynomial.


Now, let us divide x4 – 8x3 + 23x2 – 28x + 12 by x2 – 3x + 2


The division process is



Here, quotient = x2 – 5x + 6


= x2 – 2x – 3x + 6


= x(x – 2) – 3(x – 2)


= (x – 3)(x – 2)


So, the zeroes are 3 and 2


Hence, all the zeroes of the given polynomial are 1, 2 ,2 and 3.



Question 28.

Find all the zeroes of the polynomial given below having given numbers as its zeroes.

x3 + 2x2 – 2; – 2


Answer:

Given zeroes is – 2


So, (x + 2) is the factor of x3 + 2x2 – x – 2


Let us divide x3 + 2x2 – x – 2 by x + 2


The division process is



Here, quotient = x2 – 1


= (x – 1)(x + 1)


So, the zeroes are – 1 and 1


Hence, all the zeroes of the given polynomial are – 1, – 2 and 1.



Question 29.

Find all the zeroes of the polynomial given below having given numbers as its zeroes.

x3 + 5x2 + 7x + 3; – 3


Answer:

Given zeroes is – 3


So, (x + 3) is the factor of x3 + 5x2 + 7x + 3


Let us divide x3 + 5x2 + 7x + 3 by x + 3


The division process is



Here, quotient = x2 + 2x + 1


= (x + 1)2


So, the zeroes are – 1 and – 1


Hence, all the zeroes of the given polynomial are – 1, – 1 and – 3.



Question 30.

Find all the zeroes of the polynomial given below having given numbers as its zeroes.

x4 – 6x3 – 26x2 + 138x – 35;2±√3


Answer:

x4 – 6x3 – 26x2 + 138x – 35;2±√3


Given zeroes are 2 + √3 and 2 – √3


So, (x – 2 – √3)and (x – 2 + √3) are the factors of x4 – 6x3 – 26x2 + 138x – 35


⟹ (x – 2 – √3)(x – 2 + √3)


= x2 – 2x + √3 x – 2x + 4 – 2√3 – √3 x + 2√3 – 3


= x2 – 4x + 1 is a factor of given polynomial.


Consequently, x2 – 4x + 1 is also a factor of the given polynomial.


Now, let us divide x4 – 6x3 – 26x2 + 138x – 35 by x2 – 4x + 1


The division process is



Here, quotient = x2 – 2x – 35


= x2 – 7x + 5x – 35


= x(x – 7) + 5(x – 7)


= (x + 5)(x – 7)


So, the zeroes are – 5 and 7


Hence, all the zeroes of the given polynomial are – 5, 7, 2 + √3 and



Question 31.

Find all the zeroes of the polynomial given below having given numbers as its zeroes.

x4 + x3 – 34x2 – 4x + 120;2, – 2.


Answer:

x4 + x3 – 34x2 – 4x + 120;2, – 2.


Given zeroes are – 2 and 2


So, (x + 2)and (x – 2) are the factors of x4 + x3 – 34x2 – 4x + 120


⟹ (x + 2)(x – 2) = x2 – 4 is a factor of given polynomial.


Consequently, x2 – 4 is also a factor of the given polynomial.


Now, let us divide x4 + x3 – 34x2 – 4x + 120 by x2 – 4


The division process is



Here, quotient = x2 + x – 30


= x2 + 6x – 5x – 30


= x(x + 6) – 5(x + 6)


= (x + 6)(x – 5)


So, the zeroes are – 6 and 5


Hence, all the zeroes of the given polynomial are – 2 , – 6, 2 and 5.



Question 32.

Find all the zeroes of the polynomial given below having given numbers as its zeroes.

2x4 + 7x3 – 19x2 – 14x + 30;√(2, – √2)


Answer:

2x4 + 7x3 – 19x2 – 14x + 30;√(2, – √2)


Given zeroes are √2 and – √2


So, (x – √2)and (x + √2) are the factors of 2x4 + 7x3 – 19x2 – 14x + 30


⟹ (x – √2)(x + √2) = x2 – 2 is a factor of given polynomial.


Consequently, x2 – 2 is also a factor of the given polynomial.


Now, let us divide 2x4 + 7x3 – 19x2 – 14x + 30 by x2 – 2


The division process is



Here, quotient = 2x2 + 7x – 15


= 2x2 + 10x – 3x – 15


= 2x(x + 5) – 3(x + 5)


= (2x – 3)(x + 5)


So, the zeroes are – 5 and


Hence, all the zeroes of the given polynomial are – 5, – √2, √2 and



Question 33.

Find all the zeroes of the polynomial given below having given numbers as its zeroes.

2x4 – 9x3 + 5x2 + 3x – 1;2±√3


Answer:

2x4 – 9x3 + 5x2 + 3x – 1;2±√3


Given zeroes are 2 + √3 and 2 – √3


So, (x – 2 – √3)and (x – 2 + √3) are the factors of 2x4 – 9x3 + 5x2 + 3x – 1


⟹ (x – 2 – √3)(x – 2 + √3)


= x2 – 2x + √3 x – 2x + 4 – 2√3 – √3 x + 2√3 – 3


= x2 – 4x + 1 is a factor of given polynomial.


Consequently, x2 – 4x + 1 is also a factor of the given polynomial.


Now, let us divide 2x4 – 9x3 + 5x2 + 3x – 1 by x2 – 4x + 1


The division process is



Here, quotient = 2x2 – x – 1


= 2x2 – 2x + x – 1


= 2x(x – 1) + 1(x – 1)


= (2x + 1)(x – 1)


So, the zeroes are and 1


Hence, all the zeroes of the given polynomial are , 1, 2 + √3 and 2 – √3



Question 34.

Find all the zeroes of the polynomial given below having given numbers as its zeroes.

2x3 – 4x – x2 + 2;√2, – √2


Answer:

2x3 – 4x – x2 + 2;√2, – √2


Given zeroes are √2 and – √2


So, (x – √2) and (x + √2) are the factors of 2x3 – 4x – x2 + 2


⟹ (x – √2)(x + √2) = x2 – 2 is a factor of given polynomial.


Consequently, x2 – 2 is also a factor of the given polynomial.


Now, let us divide 2x3 – 4x – x2 + 2by x2 – 2


The division process is



Here, quotient = 2x – 1


So, the zeroes is


Hence, all the zeroes of the given polynomial are , and



Question 35.

Verify that are the zeroes of the cubic polynomial p(x) = 3x2 – 5x2 – 11x – 3 and then verify the relationship between the zeroes and the coefficients.


Answer:

Let p(x) = 3 x3 – 5 x2 – 11x – 3


Then, p( – 1) = 3( – 1)3 – 5( – 1)2 – 11( – 1) – 3


= – 3 – 5 + 11 – 3


= 0





= 0


p(3) = 3(3)3 – 5(3)2 – 11(3) – 3


= 81 – 45 – 33 – 3


= 0


Hence, we verified that 3, – 1 and are the zeroes of the given polynomial.


So, we take α = 3, β = – 1,


Verification


α + β + γ



αβ + βγ + γα




and αβγ


= 1



Thus, the relationship between the zeroes and the coefficients is verified.



Question 36.

Verify that the numbers given alongside of the cubic polynomial are their zeros. Also verify the relationship between the zeroes and the coefficients in each case :

x3 – 4x2 + 5x – 2;2, 1, 1


Answer:

Let p(x) = x3 – 4x2 + 5x – 2


Then, p(2) = (2)3 – 4(2)2 + 5(2) – 2


= 8 – 16 + 10 – 2


= 0


p(1) = (1)3 – 4(1)2 + 5(1) – 2


= 1 – 4 + 5 – 2


= 0


Hence, 2, 1 and 1 are the zeroes of the given polynomial x3 – 4x2 + 5x – 2.


Now, Let α = 2 , β = 1 and γ = 1


Then, α + β + γ = 2 + 1 + 1 = 4



αβ + βγ + γα = (2)(1) + (1)(1) + (1)(2)


= 2 + 1 + 2


= 5



and αβγ = 2 × 1 × 1


= 2



Thus, the relationship between the zeroes and the coefficients is verified.



Question 37.

Verify that the numbers given alongside of the cubic polynomial are their zeros. Also verify the relationship between the zeroes and the coefficients in each case :

x3 – 6x2 + 11x – 6 ;1, 2, 3


Answer:

Let p(x) = x3 – 6x2 + 11x – 6


Then, p(1) = (1)3 – 6(1)2 + 11(1) – 6


= 1 – 6 + 11 – 6


= 0


p(2) = (2)3 – 6(2)2 + 11(2) – 6


= 8 – 24 + 22 – 6


= 0
p(3) = (3)3 – 6(3)2 + 11(3) – 6


= 27 – 54 + 33 – 6


= 0


Hence, 1, 2 and 3 are the zeroes of the given polynomial x3 – 6x2 + 11x – 6.


Now, Let α = 1 , β = 2 and γ = 3


Then, α + β + γ = 1 + 2 + 3 = 6



αβ + βγ + γα = (1)(2) + (2)(3) + (3)(1)


= 2 + 6 + 3


= 11



and αβγ = 1 × 2 × 3


= 6



Thus, the relationship between the zeroes and the coefficients is verified.



Question 38.

Verify that the numbers given alongside of the cubic polynomial are their zeros. Also verify the relationship between the zeroes and the coefficients in each case :

x3 + 2x2 – x – 2; – 2 – 2, 1


Answer:

Let p(x) = x3 + 2x2 – x – 2


Then, p( – 2) = ( – 2)3 + 2( – 2)2 – ( – 2) – 2


= – 8 + 8 + 2 – 2


= 0
p(1) = (1)3 + 2(1)2 – (1) – 2


= 1 + 2 – 1 – 2


= 0


Hence, – 2, – 2 and 1 are the zeroes of the given polynomial x3 + 2x2 – x – 2.


Now, Let α = – 2 , β = – 2 and γ = 1


Then, α + β + γ = – 2 + ( – 2) + 1 = – 3



αβ + βγ + γα = ( – 2)( – 2) + ( – 2)(1) + (1)( – 2)


= 4 – 2 – 2


= 0



and αβγ = ( – 2) × ( – 2) × 1


= 4



Thus, the relationship between the zeroes and the coefficients is not verified.



Question 39.

Verify that the numbers given alongside of the cubic polynomial are their zeros. Also verify the relationship between the zeroes and the coefficients in each case :

x3 + 5x2 + 7x + 3 ; – 3, 2 – 1, – 1


Answer:

Let p(x) = x3 + 5x2 + 7x + 3.


Then, p( – 1) = ( – 1)3 + 5( – 1)2 + 7( – 1) + 3


= – 1 + 5 – 7 + 3


= 0
p( – 3) = ( – 3)3 + 5( – 3)2 + 7( – 3) + 3


= – 27 + 45 – 21 + 3


= 0


Hence, – 1, – 1 and – 3 are the zeroes of the given polynomial x3 + 5x2 + 7x + 3.


Now, Let α = – 1 , β = – 1 and γ = – 3


Then, α + β + γ = – 1 + ( – 1) + ( – 3) = – 5



αβ + βγ + γα = ( – 1)( – 1) + ( – 1)( – 3) + ( – 3)( – 1)


= 1 + 3 + 3


= 7



and αβγ = ( – 1) × ( – 1) × ( – 3)


= – 3



Thus, the relationship between the zeroes and the coefficients is verified.



Question 40.

Find a cubic polynomial having 1, 2, 3 as its zeroes.


Answer:

Let the zeroes of the cubic polynomial be


α = 1, β = 2 and γ = 3


Then, α + β + γ = 1 + 2 + 3 = 6


αβ + βγ + γα = (1)(2) + (2)(3) + (3)(1)


= 2 + 6 + 3


= 11


and αβγ = 1 × 2 × 3


= 6


Now, required cubic polynomial


= x3 – (α + β + γ) x2 + (αβ + βγ + γα)x – αβγ


= x3 – (6) x2 + (11)x – 6


= x3 – 6 x2 + 11x – 6


So, x3 – 6 x2 + 11x – 6 is the required cubic polynomial which satisfy the given conditions.



Question 41.

Find a cubic polynomial having – 3, – 2, 2 as its zeroes.


Answer:

Let the zeroes of the cubic polynomial be


α = – 3, β = – 2 and γ = 2


Then, α + β + γ = – 3 + ( – 2) + 2


= – 3 – 2 + 2


= – 3


αβ + βγ + γα = ( – 3)( – 2) + ( – 2)(2) + (2)( – 3)


= 6 – 4 – 6


= – 4


and αβγ = ( – 3) × ( – 2) × 2


= 6 × 2


= 12


Now, required cubic polynomial


= x3 – (α + β + γ) x2 + (αβ + βγ + γα)x – αβγ


= x3 – ( – 3) x2 + ( – 4)x – 12


= x3 + 3 x2 – 4x – 12


So, x3 + 3x^2 – 4x – 12 is the required cubic polynomial which satisfy the given conditions.



Question 42.

Find a cubic polynomial with the sum of its zeroes are 0, – 7 and – 6 respectively.


Answer:

Let the zeroes be α, β and γ.


Then, we have


α + β + γ = 0


αβ + βγ + γα = – 7


and αβγ = – 6


Now, required cubic polynomial


= x3 – (α + β + γ) x2 + (αβ + βγ + γα)x – αβγ


= x3 – (0) x2 + ( – 7)x – ( – 6)


= x3 – 7x + 6


So, x3 – 7x + 6 is the required cubic polynomial.



Question 43.

Find a cubic polynomial with the sum of its zeroes, sum of the products of its zeroes taken two at a time and product of its zeroes as the numbers given below:

2, – 7, – 14


Answer:

Let the zeroes be α, β and γ.


Then, we have


α + β + γ = 2


αβ + βγ + γα = – 7


and αβγ = – 14


Now, required cubic polynomial





Sox3 – 2x2 – 7x + 14 is the required cubic polynomial.



Question 44.

Find a cubic polynomial with the sum of its zeroes, sum of the products of its zeroes taken two at a time and product of its zeroes as the numbers given below:



Answer:

Let the zeroes be α, β and γ.


Then, we have





Now, required cubic polynomial





So, 6x3 + 24x2 + 3x – 2 is the required cubic polynomial which satisfy the given conditions.



Question 45.

Find a cubic polynomial with the sum of its zeroes, sum of the products of its zeroes taken two at a time and product of its zeroes as the numbers given below:



Answer:

Let the zeroes be α, β and γ.


Then, we have





Now, required cubic polynomial





So, 7x3 – 5x2 + x – 1 is the required cubic polynomial which satisfy the given conditions.



Question 46.

Find a cubic polynomial with the sum of its zeroes, sum of the products of its zeroes taken two at a time and product of its zeroes as the numbers given below:



Answer:

Let the zeroes be α, β and γ.


Then, we have





Now, required cubic polynomial





So, 10x3 – 4x2 + x – 5 is the required cubic polynomial which satisfy the given conditions.