计算：x2-y2x2-2xy+y2•y-xx+y=______．

题型：填空题难度：一般来源：不详

计算：

x2-y2

x2-2xy+y2

•

y-x

x+y

=______．

答案

原式=

(x+y)(x-y)

(x-y)2

•

y-x

x+y

=

x+y

x-y

•

y-x

x+y

=-1．
故答案为：-1．