2x^3-x^2+m=(2x+1)(x^2-x)=2x^3-2x^2+x^2-x=2x^3-x^2-x所以m=-x
可以用因式除法2x^3-x^2+m-（2x+1）*x^2=-2x^2+m-2x^2+m+（2x+1）*x=m+xm+x-1/2（2x+1）=0m=1/2
1/2
