解
(x²-2xy+y²)/(x²+x)×(x+1)/(x²-y²)
=(x-y)²/[x(x+1)]×(x+1)/(x+y)(x-y)
=(x-y)/x(x+y)=(x-y)/x(x+y)这一步中x能乘进去吗？=x-y/x的平方+xy对吗？也可以啊