# NCERT Solution For Class 8 Maths Chapter – 9 Algebraic Expression Exercise – 9.2

Q1. Find the product of the following pairs of monomials.

• 4 , 7p
• -4p , 7p
• -4p , 7pq
• 4p3 , -3p
• 4p , 0

### Solution:-

• 4 , 7p = 4 x 7p = 28p
• -4p x 7p = (-4 x 7) x  (p x q) = -28p2
• -4p x 7pq = (-4 x 7) x (p x pq) = -28p2q
• 4p3 x -3p = (4 x -3) (p3 x p ) = -12p4
• 4p x 0 = 0

### Q2. Find the area of rectangles with the following pairs  of monomials as   their lengths and breadths , respectively.

(p,q)

; (10m , 5n) ; (20x2 , 5y2) ; (4x , 3x2) ; (3mn , 4np)

Solution:-

Area of rectangle  = Length x Breadth . So , it is multiplication of two monomials.

The results can be written  square units

• P x q = pq
• 10m x 5n = 50 mn
• 20x2 x 5y2 = 100x2y2
• 4x x 3x2 == 12x3
• 3mn x 4np = 12mn2p

## Solution:-

### Q4.  Obtain the volume of rectangular boxes with the following length , breadth and height respectively.

• 5a , 3a2 , 7a4
• 2p , 4q , 8r
• Xy , 2x2y , 2xy2

Solution:-

Volume of rectangular = Length x Breadth x Height . To evaluate volume of rectangular boxes, multiply all the monomials.

• 5a x 3a2 x 7a4 = (5 x 3 x 7) (a x a2 x a4) = 105a7
• 2p x 4q x 8r = (2 x 4 x 8) (p x q x r) = 64 pqr
• Y x 2x2y x 2xy2 = ( 1 x 2 x 2) (x x x2 x x x y x y x y2) = 4x4y4
• A x 2b x 3c = (1 x 2 x 3) (a x b x c) = 6abc

### Q5. Obtain the product of

• Xy , yz , zx
• A , -a2 , a3
• 2 , 4y , 8y2 , 16y3
• A , 2b , 3c , 6abc
• M , -mn , mnp

### Solution:-

• Xy x yz x zx = x2y2z2
• A x -a2 x a3 = -a6
• 2 x 4y x 8y2 x 16y3 = 1024y6
• A x 2b x 3c x 6abc = 36a2 b2 c2
• M x -mn x mnp = -m3 n2 p

NCERT Solution For Class 8 Maths Chapter – 9 Algebraic Expression Exercise – 9.2 Q1. Find the product of the following…