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RS Aggarwal Solutions: Exercise 7E - Factorisation | Mathematics (Maths) Class 8 PDF Download

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d 2x(1 - 4x)(1 + 4x)
S o l u t i o n :
d 2x(1 - 4x)(1 + 4x)
(2x-32x3)=2x(1-16x2)=2x(1-4x)(1+4x)
Q u e s t i o n : 1 2 0
Tick ? the correct answer:
x
3
 - 144x = ?
a x(x - 12)
2
b x(x + 12)
2
c x(x - 12)(x + 12)
d none of these
S o l u t i o n :
c x(x - 12)(x + 12)
x3 - 144x=x(x2 -144)=x(x-12)(x+12)
Q u e s t i o n : 1 2 1
Tick ? the correct answer:
(2 - 50x
2
) = ?
a 2(1 - 5x)
2
b 2(1 + 5x)
2
c (2 - 5x)(2 + 5x)
d 2(1 - 5x)(1 + 5x)
S o l u t i o n :
d 2(1 - 5x)(1 + 5x)
2-50x2 =2(1-25x2)=2(1-5x)(1+5x)
Q u e s t i o n : 1 2 2
Tick ? the correct answer:
a
2
 + bc + ab + ac = ?
a (a + b)(a + c)
b (a + b)(b + c)
c (b + c)(c + a)
d a(a + b + c)
S o l u t i o n :
a (a + b)(a + c)
a2+bc +ab +ac=a2+ab+bc +ac=a(a+b)+c(a+b)=(a+c)(a+b)
Q u e s t i o n : 1 2 3
Tick ? the correct answer:
pq
2
 + q(p - 1) - 1 = ?
a (pq + 1)(q - 1)
b p(q + 1)(q - 1)
c q(p - 1)(q + 1)
d (pq - 1) (q + 1)
S o l u t i o n :
d (pq - 1) (q + 1)
pq2+q(p-1)-1=pq2+qp-q-1=pq(q+1)-1(q+1)=(pq-1)(q+1)
Q u e s t i o n : 1 2 4
Tick ? the correct answer:
ab - mn + an - bm = ?
a (a - b)(m - n)
b (a - m)(b + n)
c (a - n)(m + b)
d (m - a)(n - b)
S o l u t i o n :
b (a - m)(b + n)
ab-mn+an-bm=ab+an-mn-bm=a(b+n)-m(n+b)=(a-m)(b+n)
Q u e s t i o n : 1 2 5
Tick ? the correct answer:
ab - a - b + 1 = ?
a (a - 1)(b - 1)
b (1 - a)(1 - b)
c (a - 1)(1 - b)
d (1 - a)(b - 1)
S o l u t i o n :
a (a - 1)(b - 1)
ab-a-b+1=a(b-1)-1(b-1)=(a-1)(b-1)
Q u e s t i o n : 1 2 6
Tick ? the correct answer:
x
2
 - xz + xy - yz = ?
a (x - y)(x + z)
b (x - y)(x - z)
c (x + y)(x - z)
Page 3


    
                         
    
                        
    
                     
    
                         
    
                        
    
                        
                                                                                           
    
                                      
                                                     
    
                               
                                                     
    
                             
                                                     
    
    
     
     
     
     
     
                          
    
    
     
   
   
d 2x(1 - 4x)(1 + 4x)
S o l u t i o n :
d 2x(1 - 4x)(1 + 4x)
(2x-32x3)=2x(1-16x2)=2x(1-4x)(1+4x)
Q u e s t i o n : 1 2 0
Tick ? the correct answer:
x
3
 - 144x = ?
a x(x - 12)
2
b x(x + 12)
2
c x(x - 12)(x + 12)
d none of these
S o l u t i o n :
c x(x - 12)(x + 12)
x3 - 144x=x(x2 -144)=x(x-12)(x+12)
Q u e s t i o n : 1 2 1
Tick ? the correct answer:
(2 - 50x
2
) = ?
a 2(1 - 5x)
2
b 2(1 + 5x)
2
c (2 - 5x)(2 + 5x)
d 2(1 - 5x)(1 + 5x)
S o l u t i o n :
d 2(1 - 5x)(1 + 5x)
2-50x2 =2(1-25x2)=2(1-5x)(1+5x)
Q u e s t i o n : 1 2 2
Tick ? the correct answer:
a
2
 + bc + ab + ac = ?
a (a + b)(a + c)
b (a + b)(b + c)
c (b + c)(c + a)
d a(a + b + c)
S o l u t i o n :
a (a + b)(a + c)
a2+bc +ab +ac=a2+ab+bc +ac=a(a+b)+c(a+b)=(a+c)(a+b)
Q u e s t i o n : 1 2 3
Tick ? the correct answer:
pq
2
 + q(p - 1) - 1 = ?
a (pq + 1)(q - 1)
b p(q + 1)(q - 1)
c q(p - 1)(q + 1)
d (pq - 1) (q + 1)
S o l u t i o n :
d (pq - 1) (q + 1)
pq2+q(p-1)-1=pq2+qp-q-1=pq(q+1)-1(q+1)=(pq-1)(q+1)
Q u e s t i o n : 1 2 4
Tick ? the correct answer:
ab - mn + an - bm = ?
a (a - b)(m - n)
b (a - m)(b + n)
c (a - n)(m + b)
d (m - a)(n - b)
S o l u t i o n :
b (a - m)(b + n)
ab-mn+an-bm=ab+an-mn-bm=a(b+n)-m(n+b)=(a-m)(b+n)
Q u e s t i o n : 1 2 5
Tick ? the correct answer:
ab - a - b + 1 = ?
a (a - 1)(b - 1)
b (1 - a)(1 - b)
c (a - 1)(1 - b)
d (1 - a)(b - 1)
S o l u t i o n :
a (a - 1)(b - 1)
ab-a-b+1=a(b-1)-1(b-1)=(a-1)(b-1)
Q u e s t i o n : 1 2 6
Tick ? the correct answer:
x
2
 - xz + xy - yz = ?
a (x - y)(x + z)
b (x - y)(x - z)
c (x + y)(x - z)
d (x - y)(z - x)
S o l u t i o n :
c (x + y)(x - z)
x2-xz+xy-yz=x(x-z)+y(x-z)=(x+y) (x-z)
Q u e s t i o n : 1 2 7
Tick ? the correct answer:
(12m
2
 - 27) = ?
a (2m - 3)(3m - 9)
b 3(2m - 9)(3m - 1)
c 3(2m - 3)(2m + 3)
d none of these
S o l u t i o n :
c 3(2m - 3)(2m + 3)
12m2-27=3(4m2-9)=3 (2m-3)(2m+3)
Q u e s t i o n : 1 2 8
Tick ? the correct answer:
x
3
 - x = ?
a x(x
2
 - x)
b x(x - x
2
)
c x(1 + x)(1 - x)
d x(x + 1)(x - 1)
S o l u t i o n :
d x(x + 1)(x - 1)
x3-x=x( x2-1)=x(x-1)(x+1)
Q u e s t i o n : 1 2 9
Tick ? the correct answer:
1 - 2ab - (a
2
 + b
2
) = ?
a (1 + a - b)(1 + a + b)
b (1 + a + b)(1 - a + b)
c (1 + a + b)(1 - a - b)
d (1 + a - b)(1 - a + b)
S o l u t i o n :
c (1 + a + b)(1 - a - b)
1-2ab-(a2 +b2)=1-2ab -a2-b2=1-(2ab +a2+b2)=1-(a+b)2=(1-a-b)(1+a+b)
Q u e s t i o n : 1 3 0
Tick ? the correct answer:
x
2
 + 6x + 8 = ?
a (x + 3)(x + 5)
b (x + 3)(x + 4)
c (x + 2)(x + 4)
d (x + 1)(x + 8)
S o l u t i o n :
c (x + 2)(x + 4)
x2+6x+8=x2+4x+2x+8=x(x+4)+2(x+4)=(x+2)(x+4)
Q u e s t i o n : 1 3 1
Tick ? the correct answer:
x
2
 + 4x - 21 = ?
a (x - 7)(x + 3)
b (x + 7)(x - 3)
c (x - 7)(x - 3)
d (x + 7)(x + 3)
S o l u t i o n :
b (x + 7)(x - 3)
x2+4x-21=x2+7x-3x-21=x(x+7)-3(x+7)=(x-3)(x+7)
Q u e s t i o n : 1 3 2
Tick ? the correct answer:
y
2
 + 2y - 3 = ?
a (y - 1)(y + 3)
b (y + 1)(y - 3)
c (y - 1)(y - 3)
d (y + 2)(y - 3)
S o l u t i o n :
a (y - 1)(y + 3)
y2+2y-3=y2+3y-y-3=y(y+3)-1(y+3)=(y-1)(y+3)
Q u e s t i o n : 1 3 3
Tick ? the correct answer:
40 + 3x - x
2
 = ?
a (x + 5)(x - 8)
b (5 - x)(8 + x)
c (5 + x)(8 - x)
Page 4


    
                         
    
                        
    
                     
    
                         
    
                        
    
                        
                                                                                           
    
                                      
                                                     
    
                               
                                                     
    
                             
                                                     
    
    
     
     
     
     
     
                          
    
    
     
   
   
d 2x(1 - 4x)(1 + 4x)
S o l u t i o n :
d 2x(1 - 4x)(1 + 4x)
(2x-32x3)=2x(1-16x2)=2x(1-4x)(1+4x)
Q u e s t i o n : 1 2 0
Tick ? the correct answer:
x
3
 - 144x = ?
a x(x - 12)
2
b x(x + 12)
2
c x(x - 12)(x + 12)
d none of these
S o l u t i o n :
c x(x - 12)(x + 12)
x3 - 144x=x(x2 -144)=x(x-12)(x+12)
Q u e s t i o n : 1 2 1
Tick ? the correct answer:
(2 - 50x
2
) = ?
a 2(1 - 5x)
2
b 2(1 + 5x)
2
c (2 - 5x)(2 + 5x)
d 2(1 - 5x)(1 + 5x)
S o l u t i o n :
d 2(1 - 5x)(1 + 5x)
2-50x2 =2(1-25x2)=2(1-5x)(1+5x)
Q u e s t i o n : 1 2 2
Tick ? the correct answer:
a
2
 + bc + ab + ac = ?
a (a + b)(a + c)
b (a + b)(b + c)
c (b + c)(c + a)
d a(a + b + c)
S o l u t i o n :
a (a + b)(a + c)
a2+bc +ab +ac=a2+ab+bc +ac=a(a+b)+c(a+b)=(a+c)(a+b)
Q u e s t i o n : 1 2 3
Tick ? the correct answer:
pq
2
 + q(p - 1) - 1 = ?
a (pq + 1)(q - 1)
b p(q + 1)(q - 1)
c q(p - 1)(q + 1)
d (pq - 1) (q + 1)
S o l u t i o n :
d (pq - 1) (q + 1)
pq2+q(p-1)-1=pq2+qp-q-1=pq(q+1)-1(q+1)=(pq-1)(q+1)
Q u e s t i o n : 1 2 4
Tick ? the correct answer:
ab - mn + an - bm = ?
a (a - b)(m - n)
b (a - m)(b + n)
c (a - n)(m + b)
d (m - a)(n - b)
S o l u t i o n :
b (a - m)(b + n)
ab-mn+an-bm=ab+an-mn-bm=a(b+n)-m(n+b)=(a-m)(b+n)
Q u e s t i o n : 1 2 5
Tick ? the correct answer:
ab - a - b + 1 = ?
a (a - 1)(b - 1)
b (1 - a)(1 - b)
c (a - 1)(1 - b)
d (1 - a)(b - 1)
S o l u t i o n :
a (a - 1)(b - 1)
ab-a-b+1=a(b-1)-1(b-1)=(a-1)(b-1)
Q u e s t i o n : 1 2 6
Tick ? the correct answer:
x
2
 - xz + xy - yz = ?
a (x - y)(x + z)
b (x - y)(x - z)
c (x + y)(x - z)
d (x - y)(z - x)
S o l u t i o n :
c (x + y)(x - z)
x2-xz+xy-yz=x(x-z)+y(x-z)=(x+y) (x-z)
Q u e s t i o n : 1 2 7
Tick ? the correct answer:
(12m
2
 - 27) = ?
a (2m - 3)(3m - 9)
b 3(2m - 9)(3m - 1)
c 3(2m - 3)(2m + 3)
d none of these
S o l u t i o n :
c 3(2m - 3)(2m + 3)
12m2-27=3(4m2-9)=3 (2m-3)(2m+3)
Q u e s t i o n : 1 2 8
Tick ? the correct answer:
x
3
 - x = ?
a x(x
2
 - x)
b x(x - x
2
)
c x(1 + x)(1 - x)
d x(x + 1)(x - 1)
S o l u t i o n :
d x(x + 1)(x - 1)
x3-x=x( x2-1)=x(x-1)(x+1)
Q u e s t i o n : 1 2 9
Tick ? the correct answer:
1 - 2ab - (a
2
 + b
2
) = ?
a (1 + a - b)(1 + a + b)
b (1 + a + b)(1 - a + b)
c (1 + a + b)(1 - a - b)
d (1 + a - b)(1 - a + b)
S o l u t i o n :
c (1 + a + b)(1 - a - b)
1-2ab-(a2 +b2)=1-2ab -a2-b2=1-(2ab +a2+b2)=1-(a+b)2=(1-a-b)(1+a+b)
Q u e s t i o n : 1 3 0
Tick ? the correct answer:
x
2
 + 6x + 8 = ?
a (x + 3)(x + 5)
b (x + 3)(x + 4)
c (x + 2)(x + 4)
d (x + 1)(x + 8)
S o l u t i o n :
c (x + 2)(x + 4)
x2+6x+8=x2+4x+2x+8=x(x+4)+2(x+4)=(x+2)(x+4)
Q u e s t i o n : 1 3 1
Tick ? the correct answer:
x
2
 + 4x - 21 = ?
a (x - 7)(x + 3)
b (x + 7)(x - 3)
c (x - 7)(x - 3)
d (x + 7)(x + 3)
S o l u t i o n :
b (x + 7)(x - 3)
x2+4x-21=x2+7x-3x-21=x(x+7)-3(x+7)=(x-3)(x+7)
Q u e s t i o n : 1 3 2
Tick ? the correct answer:
y
2
 + 2y - 3 = ?
a (y - 1)(y + 3)
b (y + 1)(y - 3)
c (y - 1)(y - 3)
d (y + 2)(y - 3)
S o l u t i o n :
a (y - 1)(y + 3)
y2+2y-3=y2+3y-y-3=y(y+3)-1(y+3)=(y-1)(y+3)
Q u e s t i o n : 1 3 3
Tick ? the correct answer:
40 + 3x - x
2
 = ?
a (x + 5)(x - 8)
b (5 - x)(8 + x)
c (5 + x)(8 - x)
d (5 - x)(8 - x)
S o l u t i o n :
c (5 + x)(8 - x)
40+3x-x2=40+8x-5x-x2=8(5+x)-x(5+x)=(8-x)(x+5)
Q u e s t i o n : 1 3 4
Tick ? the correct answer:
2x
2
 + 5x + 3 = ?
a (x + 3)(2x + 1)
b (x + 1)(2x + 3)
c (2x + 5)(x - 3)
d none of these
S o l u t i o n :
b (x + 1)(2x + 3)
2x2+5x+3=2x2+2x+3x+3=2x(x+1) +3(x+1)=(2x +3) (x+1)
Q u e s t i o n : 1 3 5
Tick ? the correct answer:
6a
2
 - 13a + 6 = ?
a (2a + 3)(3a - 2)
b (2a - 3)(3a + 2)
c (3a - 2)(2a - 3)
d (3a + 1)(2a - 3)
S o l u t i o n :
c (3a - 2)(2a - 3)
6a2-13a+6=6a2-9a-4a+6=3a(2a-3)-2(2a-3)=(3a-2)(2a-3)
Q u e s t i o n : 1 3 6
Tick ? the correct answer:
4z
2
 - 8z + 3 = ?
a (2z - 1)(2z - 3)
b (2z + 1)(3 - 2z)
c (2z + 3)(3z - 1)
c (z - 1)(4z - 3)
S o l u t i o n :
a (2z - 1)(2z - 3)
4z2-8z+3=4z2-6z-2z+3=2z(2z-3)-1(2z-3)=(2z-1)(2z-3)
Q u e s t i o n : 1 3 7
Tick ? the correct answer:
3 + 23y - 8y
2
 = ?
a (1 - 8y)(3 + y)
b (1 + 8y)(3 - y)
c (1 - 8y)(y - 3)
d (8y - 1)(y + 3)
S o l u t i o n :
     )
3+23y-8y2=3+24y-y-8y2=3(1+8y)-y(1+8y)=(3-y)(1+8y)
  
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