(3+13-1-3-13+1)÷62．

题型：解答题难度：一般来源：不详

(

3 +1

3 -1

-

3 -1

3 +1

)÷

6

2

．

答案

原式=[

( 3 +1)2

( 3 -1)( 3 +1)

-

( 3 -1)2

( 3 +1)( 3 -1)

]×

2

6

=

4+2 3 -4+2 3

2

×

2

6

=2．