化简12-1+23+1的结果是______．

题型：填空题难度：一般来源：不详

化简

1

2 -1

+

2

3 +1

的结果是______．

答案

1

2 -1

+

2

3 +1

=

( 2 +1)

( 2 -1)( 2 +1)

+

2( 3 -1)

( 3 +1)( 3 -1)

=

2

+1+

3

-1=

2

+

3