已知-x+4/x(x-1)(x+2)=A/x+B/x-1+C/x+2(A,B,C为常数),求A,B,C的值
问题描述：
已知-x+4/x(x-1)(x+2)=A/x+B/x-1+C/x+2(A,B,C为常数),求A,B,C的值
答
(-x+4)/[x(x-1)(x+2)]=A/x+B/(x-1)+C/(x+2)就是右侧通分后是左侧的结果A/x+B/(x-1)+C/(x+2)通分=[A(x-1)(x+2)+Bx(x+2)+Cx(x-1)]/[x(x-1)(x+2)]=(Ax²+Ax-2A+Bx²+2Bx+Cx²-Cx)/[x(x-1)(x+2)]=[(A+B+C)x&...