-4(m+n)²+25(m-2n)²
=25(m-2n)²-4(m+n)²
=[5(m-2n)+2(m+n)][5(m-2n)-2(m+n)]
=[5m-10n+2m+2n][5m-10n-2m-2n]
=(7m-8n)(3m-12n)
=3(7m-8n)(m-4n)再帮忙解决一道因式分解题吧a的n+3次方-64a的n次方a的n+3次方-64a的n次方=a的n次方（a^3-4^3)=a的n次方(a-4)(a²+4a+4²) 后面是用了立方差公式=a的n次方(a-4)(a²+4a+16)