化简(x-y/x2-2xy+y2-xy+y2x2-y2)•xy/y-1= _ .
问题描述:
化简(
-x-y
x2-2xy+y2
)•xy+y2
x2-y2
= ___ .xy y-1
答
原式=[
-x-y (x-y)2
]•y(x+y) (x+y)(x-y)
xy y-1
=(
-1 x-y
)•y x-y
xy y-1
=
•1-y x-y
xy y-1
=-
.xy x-y
故答案是:-
.xy x-y