因为A/(x+1)+B/(x-1)=[A(x-1)+B(x+1)]/(x+1)(x-1)=[(A+B)x-(A-B)]/(x+1)(x-1),
由(x-3)/(x+1)(x-1)=A/(x+1)+B/(x-1),得:
(x-3)/(x+1)(x-1)=[(A+B)x-(A-B)]/(x+1)(x-1),
所以x-3=(A+B)x-(A-B),
所以A+B=1,A-B=3,
解方程组得:
A=2,B=-1。
因为A/(x+1)+B/(x-1)=[A(x-1)+B(x+1)]/(x+1)(x-1)=[(A+B)x-(A-B)]/(x+1)(x-1),
由(x-3)/(x+1)(x-1)=A/(x+1)+B/(x-1),得:
(x-3)/(x+1)(x-1)=[(A+B)x-(A-B)]/(x+1)(x-1),
所以x-3=(A+B)x-(A-B),
所以A+B=1,A-B=3,
解方程组得:
A=2,B=-1。
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