因为A/x-1+B/x-2=【A(x-2)+B(x-1)】/(x-1)(x-2)=【(A+B)x-(2A+B)】/(x-1)(x-2)又因为3x-4/(x-1)(x-2)=A/x-1+B/x-2所以【(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=3,2A+B=4解得A=1 ,B= 2
A=-3x^2+9x-2B=6x^2-18x+8