(2mx^2+3x+1)-(3x^2-4y^2+3x)+x^2=2mx^2+3x+1-3x^2+4y^2-3x+x^2=(2m-2)x^2+4y^2+1因为不含x^2项所以x^2项的系数必为0即：2m-2=0,m=12m^3-[3m^2-(4m+5)+m]=2m^3-3m^2+4m+5-m=2m^3-3m^2+3m+5代入m=1原式=2-3+3+5=7...