设2x^3-x^2+m=(x-1)(2x^2+ax-m)(x-1)(2x^2+ax-m)=2x^3+ax^2+mx-2x^2-ax+m=2x^3+ax^2-2x^2+mx-ax+m=2x^3+(a-2)x^2+(m-a)x+ma-2=-1a=1m-a=0m-1=0m=1
