Question

化简(

x

y

-

y

x

)÷

x-y

x

的结果是（　　）

A． 1 y

B． x+y y

C． x-y y

D．y

Answer 1

(

x

y

-

y

x

)÷

x-y

x

=

x2-y2

xy

•

x

x-y

=

(x+y)(x-y)

xy

•

x

x-y

=

x+y

y

．
故选B．