(m四次方-18m²+81)/)/(m²-6m+9)
=(m^2-9)^2/(m-3)^2
=(m-3)^2(m+3)^2/(m-3)^2
=(m+3)^2
=m^2+6m+9那(m四次方-18m²+81)/)/(m²-6m+9)计算？这个跟刚才的不是一样吗？ (m四次方-18m²+81)/)/(m²-6m+9)=[(m^2)^2-2*m^2*9+9^2]/(m^2-2*m*3+3^2)=(m^2-9)^2/(m-3)^2