问题
解答题
已知x=2+
|
答案
(
-x+y x-y
)•(x-y x+y
-1 x2
)=1 y2
•(x+y)2-(x-y)2 x2-y2 y2-x2 x2y2
=4xy•
=--1 x2y2
；4 xy
当x=2+
，y=2-3
时，(3
-x+y x-y
)•(x-y x+y
-1 x2
)=-4．1 y2
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已知x=2+
|
(
-x+y x-y
)•(x-y x+y
-1 x2
)=1 y2
•(x+y)2-(x-y)2 x2-y2 y2-x2 x2y2
=4xy•
=--1 x2y2
；4 xy
当x=2+
，y=2-3
时，(3
-x+y x-y
)•(x-y x+y
-1 x2
)=-4．1 y2