原式可化为
1/(x+1)(x-3)+2/(x-3)((x+2) +3/(x+1)(x+2)=0
两边同乘以：(x+1)(x+2)(x-3)得：
(x+2)+2(x+1)+3(x-3)=0(x≠-1,x≠-2;x≠3)
6x-5=0
x=5/6