Question

化简：

x-y

x+3y

÷

x2-y2

x2+6xy+9y2

-

2y

x+y

=______．

Answer 1

原式=

x-y

x+3y

÷

(x+y)(x-y)

(x+3y)2

-

2y

x+y

=

x-y

x+3y

×

(x+3y)2

(x+y)(x-y)

-

2y

x+y

=

x+3y

x+y

-

2y

x+y

=

x+3y-2y

x+y

=1．
故答案为：1．