Question

Factorise 9(x - y)^2 – (x + 2y)^2

Answer 1

Step-by-step explanation:

$9(x - y) ^{2} - (x + 2y)^{2}$

$9( {x}^{2} + {y}^{2} - 2xy) - ( {x}^{2} + 4 {y}^{2} + 4xy)$

$9 {x}^{2} + 9 {y}^{2} - 18xy - {x}^{2} - 4 {y}^{2} - 4xy$

$8 {x}^{2} + 5 {y}^{2} - 22xy$