Question

using suitable identities evaluate (1÷3a-b)^3

Answer 1

Using the identity (x – y) 3
= x3 - y3 - 3x2y + 3xy2

We get;
(100) 3 - 13 - [3 x (100) 2 x 1) + (3 x 100 x 12
= 1000000 – 1 30000 + 300
= 1000000 + 300 – 1 – 30000 = 970299

Answer 2

Heya ✋

Let see your answer !!!!

(1/3a - b)^3

We apply this identity

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

Hence ,

= (1/3a)^3 - (b)^3 - 3 × 1/3a × b(1/3a - b)

= 1/27a^3 - b^3 - ab(1/3a - b)

= 1/27a^3 - b^3 - b/3 + ab^2








Thanks :)))))