Question

Factorise the following:

9x² – 4(y + 2x)² 

Answer 1

To factorise, 9x² – 4(y + 2x)²

We have, (a + b)(a – b) = a² – b²

= (3x)² – [2(y + 2x)]²

= [3x + 2(y + 2x)] [3x – 2(y + 2x)]

= (3x + 2y + 4x) (3x – 2y – 4x)

= –(x + 2y) (7x + 2y)

Hence, the factors are –(x + 2y) (7x + 2y)