Dik f(x)=x²-2x-8 dan g(x)=x-4. Tentukan (g.f) (x)

[tex]$\begin{align}(gf)(x)&=g(x)\cdot f(x)\\&=(x-4)(x^2-2x-8)\\&=x(x^2-2x-8)-4(x^2-2x-8)\\&=x^3-2x^2-8x-4x^2+8x+32\\&=\boxed{x^3-6x^2+32}\end[/tex]