计算：12m2-9+23-m+2m+3．

题型：解答题难度：一般来源：不详

计算：

12

m2-9

+

2

3-m

+

2

m+3

．

答案

12

m2-9

+

2

3-m

+

2

m+3

=

12

(m+3)(m-3)

+

-2(m+3)

(m+3)(m-3)

+

2(m-3)

(m+3)(m-3)

=

12-2(m+3)+2(m-3)

(m+3)(m-3)

=

12-2m-6+2m-6

(m+3)(m-3)

=0