-2m^2-【-4m^2+(-m^2)】=-2m²+4m²+m²=3m²=3x1²=3
-2m^2-【-4m^2+(-m^2)】=-2m^2+4m^2+m^2=3m^2=3×1=3如有不明白，可以追问如有帮助，记得采纳，谢谢
原式=-2m^2-(-4m^2-m^2)=-2m^2-(-5)m^2=-2m^2+5m^2=3m^2=3×1=3
