Question

（2013•團風縣模擬）化簡：

x-y

x+3y

÷

x2-y2

x2+6xy+9y2

-

2y

x+y

=

1

．

Answer 1

分析：根據(jù)分式混合運算的法則進行計算即可．

解答：解：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．
故答案為：1．

點評：本題考查的是分式的混合運算，熟知分式混合運算的法則是解答此題的關(guān)鍵．