Question

化簡：(

1

x-y

+

1

x+y

)÷

xy

x2-y2

Answer 1

分析：此題的運算順序：先括號里，經過通分，再把除法轉化為乘法，約分化為最簡．

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

．

點評：本題的關鍵是通分、分解因式、約分，用到了平方差公式．