Question

x的平方分之4=x-1分之A+(x+1)分之B是恒等式则A=?B=?

Answer 1

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

4/(x^2-1)=(Ax+A+Bx-B)/(x^2-1)

所以A+B=0

A-B=4

解得A=2

B=-2