问题 解答题
计算:(1)
3c
ab
-
4c
ab
+
7
ab
=______;
(2)
a
a-b
+
b
b-a
=______;
(3)
a2
a+3
-
9
a+3
=______;
(4)
5
6ab
-
2
3ac
+
3
4abc
=______.
答案

(1)原式=

3c-4c+7
ab
=
7-c
ab

(2)原式=

a
a-b
-
b
a-b
=
a-b
a-b
=1;

(3)原式=

(a+3)(a-3)
a+3
=a-3;

(4)原式=

10c-8b+9
12abc

故答案为:(1)

7-c
ab
;(2)1;(3)a-3;(4)
10c-8b+9
12abc

选择题
单项选择题