问题 解答题
计算(1)
12
m2-9
+
2
3-m

(2)5
12
-9
1
3
+
1
2
48
答案

(1)

12
m2-9
+
2
3-m

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

(2)5

12
-9
1
3
+
1
2
48
=10
3
-3
3
+2
3

=9

3

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