Q4 of 86 Page 56

Expand each of the following, using suitable identities
(2a - 3b)³

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

Here x = 2a and y = 3b

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

= 8a³ – 27b³ – 18a²b + 18ab²

Therefore (2a - 3b)³ = 8a³ – 27b³ – 18a²b + 18ab²

Factorise the following using appropriate identities.

3p² - 24p + 36

Expand each of the following, using suitable identities

(x + 2y + 4z)²

Expand each of the following, using suitable identities

(-2a + 5b - 3c)²

Expand each of the following, using suitable identities

Questions · 86

2. Polynomials and Factorisation

1 2 3 4 5 6 1 2 2 2 2 2 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 5 6 1 1 1 1 1 2 3 4 5 6 7 8 9 1 1 1 1 2 2 2 2 2 3 4 5 6 7 7 7 7 8 9 10 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4 5 5

Expand each of the following, using suitable identities(2a - 3b)3