已知A/x+1+B/x-1=x-3/x^2-1
A(x-1)+B(x+1)/(x-1)(x+1)=x-3/(x+1)(x-1)
((A+B)x-(A-B))/(x-1)(x+1)=x-3/(x+1)(x-1)
A+B=1 -(A-B)=-3
A=2 B=-1
已知A/x+1+B/x-1=x-3/x^2-1
A(x-1)+B(x+1)/(x-1)(x+1)=x-3/(x+1)(x-1)
((A+B)x-(A-B))/(x-1)(x+1)=x-3/(x+1)(x-1)
A+B=1 -(A-B)=-3
A=2 B=-1