化简:(x+y-4xy/x+y)*(x-y-4xy/x-y)=
问题描述：
化简:(x+y-4xy/x+y)*(x-y-4xy/x-y)=
答
题目是不是打错了一个符号.
应该是：
（x+y-4xy/(x+y))·（x-y+4xy/(x-y)）=[(x+y)²-4xy]/(x+y)·[(x-y)²+4xy]/(x-y)
=(x-y)²/(x+y)·(x+y)²/(x-y)
=(x+y)(x-y)
=x²-y²