急求几数学问题!先化简（x+y-4xy/x+y)(x-y+4xy/x-y),再求值,其中x=-1
2019-05-23
急求几数学问题!
先化简（x+y-4xy/x+y)(x-y+4xy/x-y),再求值,其中x=-1
优质解答
先化简（x+y-4xy/x+y)(x-y+4xy/x-y)
（x+y-4xy/x+y)(x-y+4xy/x-y)
=[(x-y)^2/(x+y)][(x+y)^2/(x-y)]
=x^2-y^2
其中x=-1 没y 还求不出来
先化简（x+y-4xy/x+y)(x-y+4xy/x-y)
（x+y-4xy/x+y)(x-y+4xy/x-y)
=[(x-y)^2/(x+y)][(x+y)^2/(x-y)]
=x^2-y^2
其中x=-1 没y 还求不出来