原式=3²(m-n)²-5²(m+n)²
=[3(m-n)]²-[5(m+n)]²
=[3(m-n)-5(m+n)]*[3(m-n)+5(m+n)]
=(3m-3n-5m-5n)(3m-3n+5m+5n)
=(-2m-8n)(8m+2n)
=-4(m+4n)(4m+n)
原式=[3(m-n)-5(m+n)]*[3(m-n)+5(m+n)]
=(3m-3n-5m-5n)(3m-3n+5m+5n)
=(-2m-8n)(8m+2n)
=-4(m+4n)(4m+n)
祝你开心!希望能帮到你,如果不懂,请追问,祝学习进步!O(∩_∩)O
原式=9(m^2-2mn+n^2)-25(m^2+2mn+n^2)=9m^2+18mn+9n^2-25m^2-50mn-25n^2=-16m^2-32mn-16n^2=-16(m^2+2mn+n^2)=-16(m+n)^2
9(m-n)²-25(m+n)²=(-16m-4n)(m+4n)