Question

Factorise 15 (x-2y)^2 -8(x-2y)-16

Answer 1

225x^2+600y^2-600y+8 x +2 y-16

Answer 2

15(x - 2y)² - 8(x - 2y) - 16

Let (x - 2y) = m
15m² - 8m - 16
= 15m² - 20m + 12m - 16
= 5m( 3m - 4) + 4( 3m - 4)
= (5m + 4)(3m - 4)

now, put m = (x - 2y)

= {5(x - 2y) + 4}{3(x - 2y) - 4}
={5x - 10y + 4}{3x - 6y - 4}
=(5x - 10y + 4)(3x - 6y - 4)