问题 解答题
计算:(1)
12
m2-9
-
2
m-3

(2)
x2+9x
x2+3x
+
x2-9
x2+6x+9
答案

(1)原式=

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

(2)原式=

x(x+9)
x(x+3)
+
(x+3)(x-3)
(x+3)2
=
(x+9)
(x+3)
+
(x-3)
(x+3)
=
2x+6
x+3
=2.

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