2m^2-5m+1/2m^2 =(m^2+m^2-5m-1)/2m^2=m^2/2m^2=1/2你能不能写详细点？谢谢！(2m^2-5m+1)/2m^2=(m^2+m^2-5m-1)/2m^2 因为m^2-5m-1=0所以(m^2+m^2-5m-1)/2m^2 =(m^2+0)/2m^2 =m^2/2m^2 =0