A/(x+1)+B/(x-1)=(2x+3)/(x²-1)[(x-1)A+(x+1)B]/(x²-1)=(2x+3)/(x²-1)[Ax-A+Bx+B]/(x²-1)=(2x+3)/(x²-1)[x(A+B)+(B-A)]/(x²-1)=(2x+3)/(x²-1)x(A+B)+(B-A)=(2x+3)要使等式两边相等,则必有如下等式:A+B=2B-A=3两式相加,B=5/2=2.5A=2.5-3=-0.5