已知(3x+7)/(x-1)(x-2)=A/(x-1)+B/(x-2),求A,B的值

来源:百度知道 编辑:UC知道 时间:2024/05/28 13:17:55
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A/(x-1)+B/(x-2)
=[A(x-2)+B(x-1)]/(x-1)(x-2)
=(Ax-2A+Bx-B)/(x-1)(x-2)
=[(A+B)x-2A-B]/(x-1)(x-2)
则:(A+B)x=3x A+B=3
-2A-B=-7 2A+B=7

A+B=3……(1)
2A+B=7……(2)
(2)-(1),得
A=4
把A=4代入(1),得
B=-1

(3x+7)/(x-1)(x-2)=A/(x-1)+B/(x-2)=[(A+B)x-2A-B]/(x-1)(x-2),
A+B=3,
2A+B=-7
A=-10
B=13