把方程右边通分,得[B（x-1)(x+2)+x(x+2)+Cx(x-1)]/x(x-1)(x+2)=[(B+1+C)x^2+(B+2-C)x-2B]/x(x-1)(x+2),所以B+1+C=0,B+2-C=0,-2B=A,解得A=3,B=-3/2,C=1/2