问题
解答题
先化简，再求值：(
|
答案
原式=[
-x+y (x+y)(x-y)
]÷x-y (x+y)(x-y) 2y (x-y)2
=
×2y (x+y)(x-y) (x-y)2 2y
=
；x-y x+y
当x=1+
，y=1-2
时，2
原式=
=1+
-(1-2
)2 1+
+1-2 2
．2
搜题请搜索小程序“爱下问搜题”
先化简，再求值：(
|
原式=[
-x+y (x+y)(x-y)
]÷x-y (x+y)(x-y) 2y (x-y)2
=
×2y (x+y)(x-y) (x-y)2 2y
=
；x-y x+y
当x=1+
，y=1-2
时，2
原式=
=1+
-(1-2
)2 1+
+1-2 2
．2