Whether x2-ax-2a2 is a factor of f(x)=3x3-5ax2-4a2x+4a3

Answer 1

x^2-ax-2a^2 = (x-2a)(x+a)
3x^3-5ax^2-4a^2x+4a^3 = (3x-2a)(x-2a)(x+a) = (3x-2a)(x^2-ax-2a^2)
so, yes, it is a factor