错了吧，是求2x³-5x+3?x²+2x-1=0x²=-2x+1以下x²都有-2x+1代替则x³=x(x²)=x(-2x+1)=-2x²+x=-2(-2x+1)+x=5x-2所以原式=(5x-2)-5x+3=5x-2-5x+3=1
