a³-5a²b-24ab²
=a(a²-5ab-24ab²)
=a(a-8b)(a-3b)3ab²-9a³b²+6a³b²=3a(b²-3ab²+2a²b²)=3a(b-ab)(b-2ab)也可以提出来3ab²-9a²b²+6a³b²=3ab²(1-3a+2a²)=3ab²(1-a)(1-2a)