9【m+2n】的2次方-【2m-n】的2次方因式分解

9【m+2n】的2次方-【2m-n】的2次方=[3(m+2n)]^2-(2m-n)^2=[3(m+2n)-(2m-n)][3(m+2n)+(2m-n)]=(3m+6n-2m+n)(3m+6n+2m-n)=(m+7n)(5m+5n)=5(m+7n)(m+n) 不懂可追问满意请采纳谢谢