分式计算(x-y-4y^2/x-y)(x+y-4x^2/x+y)=?
问题描述：
分式计算(x-y-4y^2/x-y)(x+y-4x^2/x+y)=?
答
(x-y-4y^2/x-y)(x+y-4x^2/x+y)
=[(x-y)^2-4y^2]/(x-y)*[(x+y)^2-4x^2]/(x+y)
=(x-y+2y)(x-y-2y)/(x-y)*(x+y+2x)(x+y-2x)/(x+y)
=(x+y)/(x-3y)/(x-y)*(3x+y)(y-x)/(x+y)
=-(3x+y)/(x-3y)