根据题意得:
2x+1=0
x=-1/2
即方程有一个解为-1/2,代入后得:
2*(-1/2)^3-(-1/2)^2+m*(-1/2)=0
2*(-1/8)-(1/4)+m*(-1/2)=0
(-1/4)-(1/4)-(m/2)=0
(-1/2)-(m/2)=0
-1-m=0
m=-1