Question

How to factorise it (a–2b)²–5(a–2b)+6

Answer 1

let
$( a- 2b) = x$
${x}^{2} - 5x + 6 \\ {x}^{2} - 2x - 3x + 6 \\ x(x - 2) - 3(x - 2) \\ (x - 2)(x - 3)$
putting the value of X
$(a - 2b - 2) (a - 2b - 3)$