题目(x²+2)/(x(x+1)(x-1))=A/x+B/(x+1)+C/(x+2)
A/x+B/(x+1)+C/(x+2)通分,得：[(A+B+C)x²+(3A+2B+C)x+2A]/[x(x+1)(x-1)]
对应系数相等,得：A+B+C=1,3A+2B+C=0,2A=2
解出A=1,B=-3,C=3