Question

x²（x+y）（y-x）-xy（x+y）（x-y）

Answer 1

(x+y)(x-y)(-x²-xy)=(x²-y²)(-x²-xy)=- x^4+x²y²- x^3y+xy^3

Answer 2

x²（x+y）（y-x）- xy（x+y）（x-y）
= - x² (x+y)(x-y) - xy (x+y) (x-y)

= - (x+y)(x-y) ( x² + xy)
= - x (x+y)² (x-y)