问题
选择题
计算（x+y）•
|
答案
原式=（x+y）•
+x2 (x+y)(x-y)
-y2 x-y 2xy(x-y) (x-y)2
=
+x2 x-y
-y2 x-y 2xy x-y
=x2+y2-2xy x-y
=x-y．
故选B．
搜题请搜索小程序“爱下问搜题”
计算（x+y）•
|
原式=（x+y）•
+x2 (x+y)(x-y)
-y2 x-y 2xy(x-y) (x-y)2
=
+x2 x-y
-y2 x-y 2xy x-y
=x2+y2-2xy x-y
=x-y．
故选B．