Exercise 8.2

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

Instructions

(i) 4, 7p

4 × 7 p = 4 × 7 × p =

(ii) – 4p, 7p

– 4p × 7p = (-4 × 7) × (p × p) =

(iii) – 4p, 7pq

– 4p × 7pq = (-4 × 7) (p × pq) =

(iv) 4p3, – 3p

4p3 × – 3p = 4 × (-3) p3×p =

(v) 4p, 0

4p × 0 =

2. Find the areas of rectangles with the following pairs of monomials as their lengths and breadths respectively.

Instructions

We know: Area of rectangle = Length x

So, it is multiplication of two . The results can be written in units.

(p, q) : p×q =

(10m, 5n) : 10m×5n =

(20x2, 5y2) : 20x2×5y2 =

(4x, 3x2) : 4x×3x2 =

(3mn, 4np) : 3mn×4np =

3. Complete the table of products:

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

Instructions

Volume of rectangle = length x breadth x . To evaluate volume of rectangular boxes, multiply all the .

(i) 5a, 3a2, 7a4 : 5ax3a2x7a4 = 5×3×7a×a2×a4 =

(ii) 2p, 4q, 8r : 2px4qx8r = (2 × 4 × 8) (p × q × r) =

(iii) xy, 2x2y , 2xy2 : y×2x2y×2xy2 = 1×2×2x×x2×x×y×y×y2 =

(iv) a, 2b, 3c : a x 2b x 3c = (1 × 2 × 3) (a × b × c) =

5. Obtain the product of:

Instructions

(i) xy, yz, zx : xy × yz × zx =

(ii) a, – a2 , a3 : a×−a2×a3 =

(iii) 2, 4y, 8y2, 16y3 : 2×4y×8y2×16y3 =

(iv) a, 2b, 3c, 6abc : a × 2b × 3c × 6abc =

(v) m, – mn, mnp : m × – mn × mnp =

Chapter 8: Algebraic Expressions and Identities