右边通分=[A(x-2)+B(x-1)]/(x-1)(x-2)=[(A+B)x-(2A+B)]/(x-1)(x-2)=(3x-4)/(x-1)(x-2)所以(A+B)x-(2A+B)=3x-4所以A+B=32A+B=4所以A=1B=2