X-3/(X+1)(X-1)=A/X-1+B/X+1求A+B的值

热心网友

A/X-1+B/X+1=(AX+A+BX-B)/(X-1)(X+1)=[(A+B)X+(A-B)]/(X-1)(X+1)用对照系数值的方法,可得:A+B=1