1/(x(x+2)) = (1/2) * (1/x - 1/(x+2))(1/2) * (1/x - 1/(x+2)) = (1/2) * (A/x-B/(x+2))1/x - 1/(x+2) = A/x-B/(x+2)A=1B=1
令 x=1,得3A-B=2令 x=-1,得A+B=2解得,A=1,B=1