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Factorization Of Algebraic Expressions

Class 9th Mathematics RD Sharma Solution
Exercise 5.1
  1. x^3 +x-3x^2 -3 Factorize:
  2. a(a+b)3-3a^2 b(a+b) Factorize:
  3. x(x^3 -y^3)+3xy-(x-y) Factorize:
  4. a^2 x^2 +(ax^2 +1)x+a Factorize:
  5. x^2 +y-xy-x Factorize:
  6. x^3 -2x^2 y+3xy^2 -6y^3 Factorize:
  7. 6ab-b^2 +12ac-2bc Factorize:
  8. Factorize:
  9. x(x-2)(x-4)+4x-8 Factorize:
  10. (x+2)(x^2 +25)-10x^2 -20x Factorize:
  11. 2a^2 +2 root 6 ab+3b^2 Factorize:
  12. (a-b+c)^2 +(b-c+a)^2 +2(a-b+c)(b-c+a) Factorize:
  13. a^2 +b^2 +2(ab+bc+ca) Factorize:
  14. 4(x-y)^2 -12(x-y)(x+y)+9(x+y)^2 Factorize:
  15. a^2 -b^2 +2ab-c^2 Factorize:
  16. a^2 +2ab+b^2 -c^2 Factorize:
  17. a^2 +4b^2 -4ab-4c^2 Factorize:
  18. xy^9 -yx^9 Factorize:
  19. x^4 +x^2 y^2 +y^4 Factorize:
  20. x^2 -y^2 -4xz+4z^2 Factorize:
  21. x^2 +6 root 2 x+10 Factorize:
  22. x^2 -2 root 2 x-30 Factorize:
  23. x^2 - root 3 x-6 Factorize:
  24. x^2 +5 root 5 x+30 Factorize:
  25. x^2 +2 root 3 x-24 Factorize:
  26. 2x^2 - 5/6 x+ 1/12 Factorize:
  27. x^2 + 12/35 x+ 1/35 Factorize:
  28. 21x^2 -2x+ 1/21 Factorize:
  29. 5 root 5 x^2 +20x+3 root 5 Factorize:
  30. 2x^2 +3 root 5 x+531.9(2a-b)^2 -4(2a-b)-13 Factorize:
  31. 9(2a - b)^2 -4 (2a - b) - 13 Factorize:
  32. 7(x-2y)^2 -25(x-2y)+12 Factorize:
  33. 2(x+y)^2 -9(x+y)-5 Factorize:
  34. Give possible expressions for the length and breadth of the rectangle having…
  35. What are the possible expressions for the dimensions of the cuboid whose volume…
Exercise 5.2
  1. p^3 +27 Factorize each of the following expressions:
  2. y^3 +125 Factorize each of the following expressions:
  3. 1-27a^3 Factorize each of the following expressions:
  4. 8x^3 y^3 +27a^3 Factorize each of the following expressions:
  5. 64a^3 -b^3 Factorize each of the following expressions:
  6. x^3/216 -8y^3 Factorize each of the following expressions:
  7. 10x^4 y-10xy^4 Factorize each of the following expressions:
  8. 54x^6 y+2x^3 y^4 Factorize each of the following expressions:
  9. 32a^2 +108b^3 Factorize each of the following expressions:
  10. (a-2b)^3 -512b^3 Factorize each of the following expressions:
  11. Factorize each of the following expressions: (a+b)^3 -8(a-b)^3
  12. (x+2)^3 +(x-2)^3 Factorize each of the following expressions:
  13. 8x^2 y^3 -x^5 Factorize each of the following expressions:
  14. 1029-3x^3 Factorize each of the following expressions:
  15. x^6 +y^6 Factorize each of the following expressions:
  16. x^3 y^3 +1 Factorize each of the following expressions:
  17. x^4 y^4 -xy Factorize each of the following expressions:
  18. a^12 +b^12 Factorize each of the following expressions:
  19. x^3 +6x^2 +12x+16 Factorize each of the following expressions:
  20. a^3 +b^3 +a+b Factorize each of the following expressions:
  21. a^3 - 1/a^3 -2a 2/3 Factorize each of the following expressions:
  22. a^3 +3a^2 b^3 +3ab^2 +b^3 -8 Factorize each of the following expressions:…
  23. 8a^3 -b^3 -4ax+2bx Factorize each of the following expressions:
  24. Simplify (i) 173 x 173 x 173+127 x 127 x 127/173 x 173-173 x 127+127 x 127 (ii)…
Exercise 5.3
  1. 64a^3 +125b^3 +240a^2 b+300ab^2 Factorize:
  2. 125x^3 -27y^3 -225x^2 y+125xy^2 Factorize:
  3. 8/27 x^3 +1+ 4/3 x^2 +2x Factorize:
  4. 8x^3 +27y^3 +36x^2 y+54xy^2 Factorize:
  5. a^3 -3a^2 b+3ab^2 -b^3 +8 Factorize:
  6. x^3 +8y^3 +6x^2 y+12xy^2 Factorize:
  7. 8x^3 +y^3 +12x^2 y+6xy^2 Factorize:
  8. 8a^3 +27b^3 +36a^2 b+54ab^2 Factorize:
  9. 8a^3 -27b^3 -36a^2 b+54ab^2 Factorize:
  10. x^3 -12x(x-4)-64 Factorize:
  11. a^3 x^3 -3a^2 bx^2 +3ab^2 x-b^3 Factorize:
Exercise 5.4
  1. a^3 +8b^3 +64c^3 -24abc Factorize each of the following expressions:…
  2. x^3 -8y^3 +27z^3 +18xyz Factorize each of the following expressions:…
  3. 27x^3 -y^3 -z^3 -9xyz Factorize each of the following expressions:…
  4. 1/27 x^3 -y^3 +125z^3 +5xyz Factorize:
  5. 8x^3 +27y^3 -216z^3 +108xyz Factorize each of the following expressions:…
  6. 125+8x^3 -27y^3 +90xy Factorize each of the following expressions:…
  7. (3x-2y)^3 +(2y-4z)^3 +(4z-3x)^3 Factorize:
  8. (2x-3y)^3 +(4z-2x)^3 +(3y-4z)^3 Factorize each of the following expressions:…
  9. (x/2 + y + z/3)^3 + (x/3 - 2y/3 + y)^3 + (- 5x/6 - y/3 - 4z/3)^3 Factorize each…
  10. (a-3b)^3 +(3b-c)^3 +(c-a)^3 Factorize each of the following expressions:…
  11. 2 root 2 a^3 +3 root 3 b^3 +c^3 -3 root 6 abc Factorize each of the following…
  12. 3 root 3 a^3 -b^3 -5 root 5 c^3 -3 root 15 abc Factorize each of the following…
  13. 8x^3 -125y^3 +180xy+216 Factorize each of the following expressions:…
  14. 2 root 2 a^3 +16 root 2 b^3 +c^3 -12abc Factorize each of the following…
  15. Find the value of x^3 +y^3 -12xy+64,whenx+y=-4.
  16. Multiply: (i) x^2 +y^2 +z^2 -xy+xz+yzbyx+y-z (ii) x^2 +4y^2 +z^2
Cce - Formative Assessment
  1. The factors of a^2 -1-2x-x^2 areA. (a-x+1)(a-x-1) B. (a+x-1)(a-x+1) C. (a+x+1)(a-x-1)…
  2. Factorize: x^4 +x^2 +25.
  3. The factors of x^4 +x^2 =25 areA. (x^2 +3x+5)(x^2 -3x+5) B. (x^2 +3x+5)(x^2 +3x-5) C.…
  4. Factorize: x^2 -1-2a-a^2 .
  5. If a + b + c = 0, then write the value of a^3 +b^3 +c^3 .
  6. The factors of x^2 +4y^2 +4y-4xy-2x-8 areA. (x-2y-4)(x-2y+2) B. (x-y+2)(x-4y-4) C.…
  7. The factors of x^3 -x^2 y-xy^2 +y^3 areA. (x+y)(x^2 -xy+y^2) B. (x+y)(x^2 +xy+y^2) C.…
  8. Ifa^2 +b^2 +c^2 =20,anda+b+c=0,findab+bc+ca.
  9. The factors of x^3 -1+y^3 +3xyareA. (x-1+y)(x^2 +1+y^2 +x+y-xy) B. (x+y+1)(x^2 +y^2…
  10. If a + b + c = 9 and ab + bc + ca = 40, find a^2 + b^2 + c^2 .
  11. If a^2 + b^2 + c^2 = 250 and ab + bc + ca = 3, find a + b + c.
  12. The factors of 8a^2 +b^3 -6ab+1areA. (2a+b-1)(4a^2 +b^2 +1-3ab-2a) B. (2a-b+1)(4a^2…
  13. (x+y)^3 -(x-y)^3 can be factorized as:A. 2y(3x^2 +y^2) B. 2x(3x^2 +y^2) C. 2y(3y^2…
  14. Write the value of: 25^3 -75^3 +50^3 .
  15. Write the value of: 48^3 -30^3 -18^3 .
  16. The factors of x^2 -7x+6areA. x(x-6)(x-1) B. (x^2 -6)(x-1) C. (x+1)(x+2)(x-3) D.…
  17. Write the value of: (1/2)^3 + (1/3)^3 - (5/6)^3
  18. The expression (a-b)^3 +(b-c)^3 +(c-a)^3 can be factorized as:A. (a-b)(b-c)(c-a) B.…
  19. Write the value of: 30^3 +20^3 -50^3 .
  20. The expression x^4 +4 can be factorized asA. (x^2 +2x+2)(x^2 -2x+2) B. (x^2 +2x+2)(x^2…
  21. If 3x=a+b+c, then the value of (x-a)^3 +(x-b)^3 +(x-c)^3 -3(x-a)(x-b)(x-c) isA. a+b+c…
  22. If (x+y)^3 -(x-y)^3 -6y(x^2 -y^2)=ky^2 then k=A. 1 B. 2 C. 4 D. 8…
  23. Ifx^3 -3x^2 +3x-7=(x+1)(ax^2 +bx+c), then a+b+c=A. 4 B. 12 C. -10 D. 3…
  24. The value of (2.3)^3 - 0.027/(2.3)^2 + 0.69+0.09 isA. 2 B. 3 C. 2.327 D. 2.273…
  25. The value of (0.013)^3 + (0.007)^3/(0.013)^2 - 0.013 x 0.013 x 0.007 + (0.007)^2 isA.…

Exercise 5.1
Question 1.

Factorize:

x3+x-3x2-3


Answer:

Given,






Question 2.

Factorize:

a(a+b)3-3a2b(a+b)


Answer:

Given,




use the identity:

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




Question 3.

Factorize:

x(x3–y3)+3xy-(x–y)


Answer:

Given,

x(x3–y3)+3xy-(x–y)

As (x3 - y3) = (x – y)(x2 + xy + y2)

x(x3–y3)+3xy-(x–y) = x [(x – y)(x2 + xy + y2)] + 3xy-(x–y)

Take x(x-y) common to get,

x(x-y)[ (x2 + xy + y2) + 3y]


Question 4.

Factorize:

a2x2+(ax2+1)x+a


Answer:

Given,






Question 5.

Factorize:

x2+y-xy-x


Answer:

Given,







Question 6.

Factorize:

x3-2x2y+3xy2-6y3


Answer:

Given,






Question 7.

Factorize:

6ab-b2+12ac-2bc


Answer:

Given,


6ab-b2+12ac-2bc = b(6a-b)+2c(6a-b)


= (b+2c)(6a-b)



Question 8.

Factorize:


Answer:

Given,





[ BY applying (a2 - 2ab + b2 ) = (a-b)2 ]


Question 9.

Factorize:

x(x–2)(x–4)+4x-8


Answer:

Given,


X(x-2) (x-4)+4x-8 = x(x-2) (x-4)+4(x-2)


= (x-2) (x(x-4)+4)


= (x-2) (x2 - 4x + 4)


= (x-2) (x-2)2


= (x-2)3



Question 10.

Factorize:

(x+2)(x2+25)-10x2-20x


Answer:

Given,


(x+2) (x2+25) - 10x2 - 20x = (x+2) (x2+25)-10x (x+2)


= (x+2) (x2+25-10x)


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



Question 11.

Factorize:

2a2+2ab+3b2


Answer:

Given,


2a2√6ab+3b2 = (√2a)2 +2(√3×√2)ab + (√3b)2


= (√2a+√3b)2



Question 12.

Factorize:

(a-b+c)2+(b-c+a)2+2(a-b+c)(b-c+a)


Answer:

Given,


(a-b+c)2+(b-c+a)2+2(a-b+c)(b-c+a)


= (a-(b-c))2 + (a+(b-c))2 + 2(a-(b-c)) (a+(b-c))


[Applying identity: x2 + y2 +2xy = (x + y)2 , where x= a-(b-c), y= a+(b-c)]


=[(a-(b-c)) + (a+(b-c))]2
=(2a)2
=4a2

Question 13.

Factorize:

a2+b2+2(ab+bc+ca)


Answer:

Given,


a2+b2+2(ab+bc+ca)


= a2+b2+2ab+2bc+2ca


= (a+b)2+2c(a+b)


= (a+b)(a+b+2c)


Question 14.

Factorize:

4(x-y)2-12(x-y)(x+y)+9(x+y)2


Answer:

Given,


4(x-y)2 -12(x-y)(x+y)+9(x+y)2 = 4(x2-2xy+y2)-12(x2 – y2)+9(x2+y2+2xy)


= 4x2-8xy+4y2-12x2+12y2+9x2+9y+18xy


= x2+25y2+10xy


= (x)2+(5y)2+2×x×5y


= (x+5y)2



Question 15.

Factorize:

a2-b2+2ab-c2


Answer:

Given,


a2-b2+2ab-c2 = a2-(b2-2bc+c2)


= a – (b-c)2


= (a + (b-c)) (a-(b-c))


= (a+b-c) (a-b+c)



Question 16.

Factorize:

a2+2ab+b2-c2


Answer:

Given,


a2+2ab+b2-c2 = (a+b)2 – c2


= (a+b-c) (a+b+c)



Question 17.

Factorize:

a2+4b2-4ab-4c2


Answer:

Given,


a2 +4b2-4ab-4c2 = (a)2+ (2b)2 – 2×a×2b-4c2


= (a-2b)2 – (2c)2


= (a-2b-2c)(a-2b+2c)



Question 18.

Factorize:

xy9–yx9


Answer:

Given,


xy9 - yx9 = xy (y8-x8)


= xy ((y4)2 – (x4)2)


= xy (y4+x4) (y4 - x4)


= xy (y4+x4) (y2-x2) (y2+x2)


= xy (y4+x4) (y2+x2) (y – x) (y+x)



Question 19.

Factorize:

x4+x2y2+y4


Answer:

Given,


x4+x2y2+y4 = x4+2x2y2+y4 – x2y2


= (x2y2)2 – (xy)2


= (x2+ y2 – xy) (x2+ y2 + xy)



Question 20.

Factorize:

x2-y2-4xz+4z2


Answer:

Given,


x2 – y2 - 4xz + 4z2 = x2 – 4xz +4z2 – y2


= (x)2 - 2×x×2z+(2z)2 – y2


= (x-2z)2 – y2


= (x - 2z - y) (x – 2z + y)


= (x – y – 2z) (x + y – 2z)



Question 21.

Factorize:

x2+6x+10


Answer:

Given,


x2+6√2x+10 = x2+√2x + 10


= x(x+√2) + 5√2 (x +√2)


= (x+√2) (x+5√2)



Question 22.

Factorize:

x2-2x-30


Answer:

Given,


x2 - 2√2x – 30 = x2 - 5√2x+3√2x-30


= x(x-5√2) +3√2 (x - 5√2)


= (x-5√2) (x+3√2)



Question 23.

Factorize:

x2-x-6


Answer:

Given,


X2 - √3x – 6 = x2 - 2√3x + √3x – 6


= x (x - 2√3) + √3 (x-2√3)


= (x + √3) (x - 2√3)



Question 24.

Factorize:

x2+5x+30


Answer:

Given,


x2 + 5√5x + 30 = x2 + 3√5x + 2√5x + 30


= x (x + 3√5) + 2√5 (x + 3√5)


= (x + 3√5) (x + 2√5)



Question 25.

Factorize:

x2+2x-24


Answer:

Given,


x2 + 2√3x – 24 = x2 + 4√3x - 2√3x – 24


= x(x + 4√3) - 2√3 (x + 4√3)


= (x + 4√3) (x - 2√3)



Question 26.

Factorize:

2x2-x+


Answer:

Given,







Question 27.

Factorize:

x2+x+


Answer:

Given,






Question 28.

Factorize:

21x2-2x+


Answer:

Given,






Question 29.

Factorize:

5x2+20x+3


Answer:

Given,


5√5x2+20x+3√5 = 5√5x2 + 15x + 5x + 3√5


= 5x(√5x+3) + √5 (√5x+3)


= (5x +√5) (√5x + 3)



Question 30.

Factorize:

2x2+3x+531.9(2a-b)2-4(2a-b)-13


Answer:

Given,


2x2+3√5x+5 = 2x2 + 2√5x+ √5x+5


= 2x (x + √5) +√5 (x+√5)


= (2x+√5) (x+√5)



Question 31.

Factorize:

9(2a – b)2 –4 (2a – b) – 13


Answer:

Given,


9(2a – b)2 –4 (2a – b) – 13


Let us assume (2a – b) = x


9x2 – 4x – 13


9x2 – 13x + 9x – 13


x(9x – 13)+1 (9x + 3)


(9x – 13) (x + 1)


[9(2a – b) – 13] [2a – b + 1]


(18a – 9b – 13) (2a – b + 1)



Question 32.

Factorize:

7(x-2y)2-25(x-2y)+12


Answer:

Given,


7(x – 2y)2 – 25 (x – 2y) + 12


Let a = (x – 2y),


So we have,


= 7a2 – 25a + 12


= 7a2 – 21a – 4a + 12


= 7a(a - 3) -4 (a - 3)


= (7a – 4) (a - 3)


Put a = (x – 2y)


= {7(x – 2y) – 4} (x – 2y - 3)


= (7x – 14y -4) (x – 2y - 3)



Question 33.

Factorize:

2(x+y)2-9(x+y)-5


Answer:

Given,


2(x+y)2 – 9(x+y) – 5,


= 2a2 -9a – 5


Let (x+y) = a


= 2a2 – 10a+a – 5


= 2a (a-5) +1(a-5)


= (2a+1) (a-5)


= {2(x+y)+1}(x+y-5)


(2x+2y+1) (x+y-5)



Question 34.

Give possible expressions for the length and breadth of the rectangle having 35y2+13y-12 as its area.


Answer:

We know that,


Area of rectangle = length × breadth


Given,


35y2 + 13y – 12 = 35y2 + 28y – 15y -12


= 7y(5y+4) -3 (5y + 4)


= (7y – 3) (5y + 4)


Thus,


Length = (7y – 3), then breadth = (5y + 4)


Length = (5y + 4), then breadth = (7y – 3)



Question 35.

What are the possible expressions for the dimensions of the cuboid whose volume is 3x2-12x.


Answer:

Given,


We know that,


Volume of cuboids = length × breadth × height


Given,


3x2 – 12x = 3x (x-4)


Thus,


Dimensions of cuboids are –





Exercise 5.2
Question 1.

Factorize each of the following expressions:

p3+27


Answer:

Given,


P3+27,


= p3 + (3)3 [∵ a3+b3 = (a+b)(a2 – 2ab +b2)


= (p + 3) (p2 + 9 – 3p)



Question 2.

Factorize each of the following expressions:

y3+125


Answer:

Given,


y3+125,


= y3 + (5)3 [∵ a3+b3 = (a+b)(a2 – 2ab +b2)


= (y + 5) (y2 – 5y + 25)



Question 3.

Factorize each of the following expressions:

1-27a3


Answer:

Given,


1 – 27a3,


= 1 – (3a)3


= (1 – 3a) (1+9a2+3a)



Question 4.

Factorize each of the following expressions:

8x3y3+27a3


Answer:

Given,


8x3 y3 +27a3,


= (2xy)3 + (3a)3


= (2xy + 3a) (4x2 y2 +9a2 – 6axy)



Question 5.

Factorize each of the following expressions:

64a3-b3


Answer:

Given,


64a3 - b3,


= (4a)3 - (b)3


= (4a - b) (16a2 + b2 + 4ab)



Question 6.

Factorize each of the following expressions:

-8y3


Answer:

Given,





Question 7.

Factorize each of the following expressions:

10x4y-10xy4


Answer:

Given,


10x4 y – 10xy4,


= 10xy (x3 - y3)


= 10xy (x - y) (x2 + xy – y2)



Question 8.

Factorize each of the following expressions:

54x6y+2x3y4


Answer:

Given,


54x6 y + 2x3 y4,


= 2x3 y (27x3 + y3)


= 2x3 y {(3x)3 + (y)3}


= 2x3 y (3x + y) (9x2 + y2 – 3xy)



Question 9.

Factorize each of the following expressions:

32a2+108b3


Answer:

Given,


32a3+108b3,


= 4 (8a3+27b3)


= 4 { (2a)3 + (3b)3 }


= 4 (2a + 3b) (4a2 +9b2 – 6ab)



Question 10.

Factorize each of the following expressions:

(a-2b)3-512b3


Answer:

Given,


(a – 2b)3 – 512b3


= (a – 2b)3 – (8b)3


= (a – 2b – 8b) {(a – 2b)2 +(8b)2 +(a – 2b) 8b}


= (a – 10b) (a2 +4b2 – 4ab +64b2 +8ab – 16b2)


= (a – 10b) (a2 +52b2 +4ab)



Question 11.

Factorize each of the following expressions:
(a+b)3-8(a-b)3


Answer:

Given,


(a + b)3 – {2(a – b)}3


= {(a + b) –2(a - b)} { (a+b)2 +4(a-b)2 +2(a+b)(a - b)} [ By using: x3 - y3 = (x - y)(x2 + y2 +xy)


= (a + b – 2a + 2b)(a2 + b2 + 2ab + 4a2 +4b2 – 8ab + 2a2 – 2b2)


= (3b – a) (7a2 +3b2 - 6ab)


Question 12.

Factorize each of the following expressions:

(x+2)3+(x-2)3


Answer:

Given,


(x+2)3 + (x - 2)3 = (x + 2 + x - 2) { (x + 2)2 + (x - 2)2 – (x + 2)(x - 2) }


= 2x (x2 + 4 + 4x + x2 + 4 – 4x – x2 + 4)


= 2x (x2 +12)



Question 13.

Factorize each of the following expressions:

8x2y3-x5


Answer:

Given,


8x2y3 – x5


= x2 (8y3 – x3)


= x2 { (2y)2 – (x)3}


= x2 (2y - x) (4y2 + x2 + 2xy)



Question 14.

Factorize each of the following expressions:

1029-3x3


Answer:

Given,


1029 – 3x3


= 3 (343 – x3)


= 3 { (7)3 – (x)3}


= 3 (7 - x) (49 +x2 +7x)



Question 15.

Factorize each of the following expressions:

x6+y6


Answer:

Given,


X6 + y6 = (x2)3 + (y2)3


= (x2 + y2) (x4 +y4 – x2y2)



Question 16.

Factorize each of the following expressions:

x3y3+1


Answer:

Given,


X3y3 + 1 = (xy)3 +(1)3


= (xy + 1) (x2 y2 +1 - xy)



Question 17.

Factorize each of the following expressions:

x4y4-xy


Answer:

Given,


X4y4 – xy = xy (x3y3 -1)


= xy { (xy)3 – (1)3}


= xy (xy -1) (x2y2 +1+xy)



Question 18.

Factorize each of the following expressions:

a12+b12


Answer:

Given,


a12 +b12 = (a4)3 + (b4)3


= (a4 + b4)(a3 +b3 – a4b4)



Question 19.

Factorize each of the following expressions:

x3+6x2+12x+16


Answer:

Given,


X3 +6x212x+16 = (x3 + 6x2+12x+8)+8


= (x+2)3 + 8 [∵ (a+b)3 = a3 + b3 +3ab(a+b)]


= (x+2)3 + (2)3


= (x+2+2) {(x+2)2 +4 – 2 (x+2)}


= (x+4)(x2+4+4x+4 - 2x - 4)


= (x+4)(x2+2x+4)



Question 20.

Factorize each of the following expressions:

a3+b3+a+b


Answer:

Given,


a3+b3+a+b = (a3 + b3) + (a+b)


= (a+b) (a2 – ab +b2) +a+b


= (a+b)(a2 – ab +b2+1)



Question 21.

Factorize each of the following expressions:

a3--2a


Answer:

Given,








Question 22.

Factorize each of the following expressions:

a3+3a2b3+3ab2+b3-8


Answer:

Given,


A3+3a2 b+3ab2+b3-8 = (a3 +3a2b +3ab2+b3) – 8


= (a+b)3 -8


= (a+b)3 – (2)3


= (a+b -2) { (a+b)2 + (2)2 + 2(a+b) }


= (a+b - 2) (a2+b2 + 2ab+4+2a+2b)



Question 23.

Factorize each of the following expressions:

8a3-b3-4ax+2bx


Answer:

Given,


8a3 – b3 – 4 ax + 2bx = (2a)3 – (b)3 – 2x(2a - b)


= (2a - b) (4a2 + b2 +2ab)-2x(2a - b)


= (2a - b) (4a2 + b2 +2ab – 2x)



Question 24.

Simplify

(i)

(ii)

(iii)


Answer:

(i) Given,





(ii) Given,






(ii) Given,


=







Exercise 5.3
Question 1.

Factorize:

64a3+125b3+240a2b+300ab2


Answer:

Given,


64a3 + 125b3 + 240a2b + 300ab2,


= (4a)3 + (5b)3 + 60ab (4a + 5b)


= (4a)3 + (5b)3 + 3×4a×5b (4a + 5b)


= (4a+5b)3


= (4a+5b)(4a+5b)(4a+5b)



Question 2.

Factorize:

125x3-27y3-225x2y+125xy2


Answer:

Given,


125x3-27y3-225x2y+125xy2,


= (5x)3 – (3y)3 – 45xy (5x – 3y)


= (5x)3 – (3y)3 – 3×5x×3y (5x – 3y)


= (5x – 3y)3


= (5x – 3y) (5x – 3y) (5x – 3y)



Question 3.

Factorize:

x3+1+x2+2x


Answer:

Given,








Question 4.

Factorize:

8x3+27y3+36x2y+54xy2


Answer:

Given,


8x3+27y3+36x2y+54xy2,


= (2x)3+(3y)3 +18xy (2x +3y)


= (2x)3+(3y)3 +3×2x×3y (2x +3y)


= (2x+3y)3


= (2x +3y) (2x +3y) (2x +3y)



Question 5.

Factorize:

a3-3a2b+3ab2-b3+8


Answer:

Given,


a3 - 3a2b + 3ab2 - b3 + 8,


= {(a)3 – (b)3 -3ab (a-b)} +8


= (a-b)3 + (2)3


= (a – b +2) {(a - b)2 +(2)2 +2(a - b)}


= (a - b +2)(a2 -2ab +b2 +4+2a – 2b)



Question 6.

Factorize:

x3+8y3+6x2y+12xy2


Answer:

Given,


x3+8y3+6x2y+12xy2,


= (x)3+(2y)3 +6xy (x +2y)


= (x)3+(2y)3 +3×x×2y (x +2y)


= (x+2y)3


= (x +2y) (x +2y) (x +2y)



Question 7.

Factorize:

8x3+y3+12x2y+6xy2


Answer:

Given,


8x3+y3+12x2y+6xy2,


= (2x)3+(y)3 +6xy (2x +y)


= (2x)3+(y)3 +3×2x×y (2x +y)


= (2x+y)3


= (2x +y) (2x +y) (2x +y)



Question 8.

Factorize:

8a3+27b3+36a2b+54ab2


Answer:

Given,


8a3+27b3+36a2b+54ab2,


= (2a)3+(3b)3 +18ab (2a + 3b)


= (2a)3 + (3b)3 +3×2a×3b (2a +3b)


= (2a +3b)3


= (2a +3b) (2a + 3b) (2a +3b)



Question 9.

Factorize:

8a3-27b3-36a2b+54ab2


Answer:

Given,


8a3 - 27b3 - 36a2b+54ab2,


= (2a)3 - (3b)3 - 18ab (2a - 3b)


= (2a)3 - (3b)3 - 3×2a×3b (2a – 3b)


= (2a - 3b)3


= (2a - 3b) (2a - 3b) (2a - 3b)



Question 10.

Factorize:

x3-12x(x-4)-64


Answer:

Given,


x3-12x(x-4)-64,


= (x)3 -12x (x - 4) – (4)3


= (x)3 –(4)3 - 3×x×4 (x - 4)


= (x - 4)3


= (x - 4) (x - 4) (x - 4)



Question 11.

Factorize:

a3x3-3a2bx2+3ab2x-b3


Answer:

Given,


a3x3-3a2bx2+3ab2x-b3,


= (ax)3 – 3abx(ax-b) – (b)3


= (ax)3 – (b)3 – 3abx (ax-b)


= (ax-b)3


= (ax-b) (ax-b) (ax-b)




Exercise 5.4
Question 1.

Factorize each of the following expressions:

a3+8b3+64c3-24abc


Answer:

Given,


=


This can be written in form


=


=


Hence,


=


=


Thus the required factors of



Question 2.

Factorize each of the following expressions:

x3-8y3+27z3+18xyz


Answer:

Given,


=


This can be written in form,


=


=


=


=


Thus the required factors of



Question 3.

Factorize each of the following expressions:

27x3-y3-z3-9xyz


Answer:

Given,


=


This can be written in form ,


=


=


So ,


=


=


Thus the factors of



Question 4.

Factorize:

x3-y3+125z3+5xyz


Answer:

Given,


=


This can be written in form ,


=


=


=


=


Thus the factors of



Question 5.

Factorize each of the following expressions:

8x3+27y3-216z3+108xyz


Answer:

Given,


=


This can be written in form ,


=


=


=


=


Thus the factors of




Question 6.

Factorize each of the following expressions:

125+8x3-27y3+90xy


Answer:

Given,


=


This can be written in form ,


=


=


=


=


Thus the factors of



Question 7.

Factorize:

(3x-2y)3+(2y-4z)3+(4z-3x)3


Answer:

Given,


=


Let


=


Here ,


=


=


Hence ,


=


=


= = 3



Question 8.

Factorize each of the following expressions:

(2x-3y)3+(4z-2x)3+(3y-4z)3


Answer:

Given,


=


Let


Then ,


=


Here ,


=


Hence ,


=


=


= .



Question 9.

Factorize each of the following expressions:



Answer:

Given,


=


Let


Then ,


=


Here ,


= = 0


=


Hence ,


=


=


=



Question 10.

Factorize each of the following expressions:

(a-3b)3+(3b-c)3+(c-a)3


Answer:

Given,


=


Let


Then,


=


Here ,


= = 0


=


Hence,


=


=


=



Question 11.

Factorize each of the following expressions:

2a3+3b3+c3-3abc


Answer:

Given,


=


This can be written in form ,


=


And ,


Hence,


=


=



Question 12.

Factorize each of the following expressions:

3a3-b3-5c3-3abc


Answer:

Given,


=


This can be written in form .


=


And ,


=


=



Question 13.

Factorize each of the following expressions:

8x3-125y3+180xy+216


Answer:

Given,


=


This can be written in form ,


=


And ,


Hence ,


= =


=


Thus the factors of




Question 14.

Factorize each of the following expressions:

2a3+16b3+c3-12abc


Answer:

Given,


=


This can be written in form ,


=


And ,


Hence ,


=


=


Thus the factors of



Question 15.

Find the value of x3+y3-12xy+64,whenx+y=-4.


Answer:

Given,


=


= x + y = -4 Given


= x+y+4 = 0


This can be written in form ,


=


And ,


=


= 0 ×


= 0



Question 16.

Multiply:

(i) x2+y2+z2-xy+xz+yzbyx+y-z

(ii) x2+4y2+z2+2xy+xz-2yzbyx-2y-z

(iii) x2+4y2+2xy+-3x+6y+9byx-2y+3

(iv) 9x2+25y2+15xy+12x-20y+16by3x-5y+4


Answer:

(i) Given,


=


Multiply the above expression by ( x+ y – z)


=


=


=


=


(ii) Given,


=


Multiply above expression by (x-2y-z)


Then ,


=


=


By formula…


=


iii) we have


=


(iii) Given,


=


Multiply above equation by ( x- 2y +3 )


=


=


=


=


(iv) Given,


=


Multiply above equation by (3x – 5y +4)


We got,


=


=


=


=




Cce - Formative Assessment
Question 1.

The factors of a2-1-2x-x2 are
A. (a-x+1)(a-x-1)

B. (a+x-1)(a-x+1)

C. (a+x+1)(a-x-1)

D. none of these


Answer:

We have,


=


=


=


Thus, the factors of


Question 2.

Factorize: x4+x2+25.


Answer:

We have,


First we rewrite the question,

x4 + x2 + 25 = (x2)2 + 2.x2.5 + 52 - 9x2

= {(x2)2 + 2.x2.5 + 52} – (3x)2 [By using a2 + 2ab + b2 = (a + b)2]

= {x2 + 5}2 – (3x)2 [ By using a2 – b2 = (a + b) (a - b)

= (x2 + 5 +3x) ( x2 + 5 -3x)



Thus , the factors of .


Question 3.

The factors of x4+x2=25 are
A. (x2+3x+5)(x2-3x+5)

B. (x2+3x+5)(x2+3x-5)

C. (x2+x+5)(x2-x+5)

D. none of these


Answer:

We have,


=


Adding and subtracting 9x2 in the equation


=


=


=


Thus the factors of (x4+x2+25) are


Question 4.

Factorize: x2-1-2a–a2.


Answer:

We have ,


=


Taking -1 as common from last three terms


=


=


=


=


Thus the factors of



Question 5.

If a + b + c = 0, then write the value of a3+b3+c3.


Answer:

We have,


=


When ( a + b + c) = 0 Given


=


=


=



Question 6.

The factors of x2+4y2+4y-4xy-2x-8 are
A. (x-2y-4)(x-2y+2)

B. (x-y+2)(x-4y-4)

C. (x+2y-4)(x+2y+2)

D. none of these


Answer:

We have ,


=


=


Let a = ( x-2y) , then the expression becomes ,


=


=


= a(a-4) + 2( a -4)


=


Put a = ( x -2y)


=


Thus the factors of


Question 7.

The factors of x3-x2y-xy2+y3are
A. (x+y)(x2-xy+y2)

B. (x+y)(x2+xy+y2)

C. (x+y)2(x-y)

D. (x-y)2(x+y)


Answer:

We have,


=


=


As


=


=


=


=


Question 8.

Ifa2+b2+c2=20,anda+b+c=0,findab+bc+ca.


Answer:

We have ,


=


=


=


Then,


=


=


=


=



Question 9.

The factors of x3-1+y3+3xyare
A. (x-1+y)(x2+1+y2+x+y-xy)

B. (x+y+1)(x2+y2+1-xy-x-y)

C. (x-1+y)(x2-1-y2+x+y+xy)

D. 3(x+y-1)(x2+y2-1)


Answer:

We have ,


=


=


=


Thus the factors of


Question 10.

If a + b + c = 9 and ab + bc + ca = 40, find a2 + b2 + c2.


Answer:

We have ,


=


=


=


Then,


=


=


=


=



Question 11.

If a2 + b2 + c2 = 250 and ab + bc + ca = 3, find a + b + c.


Answer:

We have,


=


=


=


Then,


=


=


=


= =



Question 12.

The factors of 8a2+b3-6ab+1are
A. (2a+b-1)(4a2+b2+1-3ab-2a)

B. (2a-b+1)(4a2+b2-4ab+1-2a+b)

C. (2a+b+1)(4a2+b2+1-2ab-b-2a)

D. (2a-1+b)(4a2+1-4a-b-2ab)


Answer:

We have ,


=


=


=


Thus the factors of are .


Question 13.

(x+y)3-(x-y)3 can be factorized as:
A. 2y(3x2+y2)

B. 2x(3x2+y2)

C. 2y(3y2+x2)

D. 2x(x2+3y2)


Answer:

We have ,


=


Applying formulas,


=


=


=


=


Thus the factors of are


Question 14.

Write the value of: 253–753+503.


Answer:

We have,


=


Let a = 25 , b = -75 , c = 50 ,


Then the expression becomes as ,


=


=


Here ,


Hence,


=


=


=


=


=



Question 15.

Write the value of: 483–303-183.


Answer:

We have,


=


Let a = 48 , b = -30 , c = -18


Then the expression becomes ,


=


=


Here,


=


Hence,


=


=


=


=


=



Question 16.

The factors of x2-7x+6are
A. x(x-6)(x-1)

B. (x2-6)(x-1)

C. (x+1)(x+2)(x-3)

D. (x-1)(x+3)(x-2)


Answer:

We have,


=


Adding and subtracting 1 in the equation


=


=


=


=


Thus the factors of


Question 17.

Write the value of:


Answer:

We have ,


=


Let


=


Here,


=


Hence ,


=


=


=


=


=



Question 18.

The expression (a-b)3+(b-c)3+(c-a)3 can be factorized as:
A. (a-b)(b-c)(c-a)

B. 3(a-b)(b-c)(c-a)

C. -3(a-b)(b-c)(c-a)

D. (a+b+c)(a2+b2+c2-ab-bc-ca)


Answer:

We have,


Let


So,


If a+b+c = 0 , then,


=


=


Question 19.

Write the value of: 303+203-503.


Answer:

We have ,


=


Let


=


Here ,


=


Hence,


=


=


=


=


=



Question 20.

The expression x4+4 can be factorized as
A. (x2+2x+2)(x2-2x+2)

B. (x2+2x+2)(x2+2x-2)

C. (x2-2x-2)(x2-2x+2)

D. (x2+2)(x2-2)


Answer:

We have ,


=


=


=


=


=


Question 21.

If 3x=a+b+c, then the value of (x-a)3+(x-b)3+(x-c)3-3(x-a)(x-b)(x-c) is
A. a+b+c

B. (a-b)(b-c)(c-a)

D. 0

D. none of these


Answer:

We have,


= 3x = a+b+c


Let


So,


= [ a +b + c = 3x ] given


=


Now,


Question 22.

If (x+y)3-(x-y)3-6y(x2-y2)=ky2 then k=
A. 1

B. 2

C. 4

D. 8


Answer:

We have,


=


=


=


=


= k = 8 .


Question 23.

Ifx3-3x2+3x-7=(x+1)(ax2+bx+c), then a+b+c=
A. 4

B. 12

C. -10

D. 3


Answer:

We have,


=


=


=


By compairing both sides ,


= a = 1


= a + b = -3


= b + c = 3


= c = -7


Thus , a + (b + c) = 1+3 = 4.


Question 24.

The value ofis
A. 2

B. 3

C. 2.327

D. 2.273


Answer:

We have,


=


=[


Hence,


=


= ( 2.3 – 0.3 ) = 2 .


Question 25.

The value of is
A. 0.006

B. 0.02

C. 0.0091

D. 0.00185


Answer:

We have,


= [


Hence,


=


= 0.013 + 0.007 = 0.020