计算(x-y+4xyx-y)(x+y-4xyx+y)的正确结果是(  ) A.y2-x2 B.x2-y2 C.(x-y)2x2-y2(x≠y) D.x2-y2x2+y2\;

问题描述:

计算(x-y+

4xy
x-y
)(x+y-
4xy
x+y
)的正确结果是(  )
A. y2-x2
B. x2-y2
C.
(x-y)2
x2-y2
(x≠y)
D.
x2-y2
x2+y2
\

(x-y+

4xy
x-y
)(x+y-
4xy
x+y
)
=
(x-y)2+4xy
x-y
(x+y)2-4xy
x+y

=
(x+y)2
x-y
(x-y)2
x+y

=(x+y)(x-y)=x2-y2,故选B.