6a^2-a-9a^3
问题描述：
6a^2-a-9a^3
答
6a^2-a-9a^3
=-a(9a^2-6a+1)
=-a(3a-1)^2
6a^2-a-9a^3
6a^2-a-9a^3
=-a(9a^2-6a+1)
=-a(3a-1)^2