Question

Factorise the following:
(x + 4)² - 5xy - 20y - 6y²

Answer 1

(x + 4)² - 5xy - 20y - 6y²
= (x + 4)² - 5y(x + 4) - y²
= (x + 4)² - 6y(x + 4) + y(x + 4) - 6y²
= (x + 4)(x + 4 - 6y) + y(x + 4 - 6y)
= (x + 4 - 6y)(x + 4 + y)
= (x - 6y + 4)(x + y + 4).