Question

约分 -(x+y)(x-y)^2/(y+x)(y^2-x^2)

Answer 1

原式=-（x+y）(x-y)(x-y)/(x+y)(y-x)(y+x)=(x-y)(x+y)

很简单的，都约掉了。
很感谢你向我们团队提问，抱歉现在才来解答

Answer 2

-(x+y)(x-y)^2/(y+x)(y^2-x^2)
=-(x^2-y^2)(x-y)/(y+x)(y^2-x^2)
=(x-y)/(y+x)