Question

2x/(x^2-4)=A/(x+2)+B/(x-2)是恒等式,那么A=?B=?

Answer 1

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

=[A（X-2）+B(X+2)]/(x^2-4)

=[(A+B)X-2(A-B)]/(x^2-4)

因为等式恒成立.

所以,A+B=2,-2(A-B）=0

解之,A=B=1