问题 填空题
A
x+1
+
B
x+2
=
x-3
x2+3x+2
,则
A
B
=______.
答案

A
x+1
+
B
x+2
=
A(x+2)+B(x+1)
(x+1)(x+2)
=
(A+B)x+2A+B
x2+3x+2
=
x-3
x2+3x+2

∴A+B=1,2A+B=-3,

解得:A=-4,B=5,

A
B
=-
4
5

故答案为:-

4
5

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