Question

4(x-y)2 -12(x-y)(x-y)-9(x+y)2

Answer 1

$4(x - y) {}^{2} - 2 \times 2(x - y) \times 3(x + y) +( 3(x + y) {)}^{2}$

$= (2(x - y) - 3(x + y) {)}^{2}$

$= (2x - 2y - 3x - 3y) {}^{2}$

$= ( - x - 5y) {}^{2}$

$= (x + 5y) {}^{2}$

$x {}^{2} + 10xy + 25 {y}^{2}$