(1)2x(x+y)-4(x+y)^2
=(x+y)(2x-4x-4y)
=(x+y)(-2x-4y)
=-2(x+y)(x+2y)
(2)(x+y)(b-a)+(x-y)(a-b)
=(-x-y)(a-b)+(x-y)(a-b)
=(a-b)(-x-y+x-y)
=-2y(a-b)
(1)2x(x+y)-4(x+y)^2
=(x+y)(2x-4x-4y)
=(x+y)(-2x-4y)
=-2(x+y)(x+2y)
(2)(x+y)(b-a)+(x-y)(a-b)
=(-x-y)(a-b)+(x-y)(a-b)
=(a-b)(-x-y+x-y)
=-2y(a-b)