Question

(x-2y)²+7(x-2y)+12 factorise

Answer 1

Let x-2y = a

Therefore
a² + 7a +12
a² + 4a + 3a + 12
a(a+4) + 3(a+4)
(a+3) (a+4)
Since a = x -2y
(x-2y+3) (x-2y+4) is the answer