Question

化简：(

1

x-y

+

1

x+y

)÷

xy

x2-y2

Answer 1

分析：此题的运算顺序：先括号里，经过通分，再把除法转化为乘法，约分化为最简．

解答：解：(

1

x-y

+

1

x+y

)÷

xy

x2-y2

=

x+y+x-y

(x-y)(x+y)

•

x2-y2

xy

=

2

y

．

点评：本题的关键是通分、分解因式、约分，用到了平方差公式．