162

f\left(x\right)=\frac{3x^3-11x^2-6x+8}{x-4}

\begin{matrix} &3x^2+x-2\\ x-4&3x^3-11x^2-6x+8\\ &3x^3+12x^2\\ &--------\\ &x^2-6x\\ &x^2-4x\\ &--------\\ &-2x+8\\ &-2x+8\\ &--------\\ &0 \end{matrix}
eli
\left(x-7\right)\left(3x^2+x-2\right)=0
x-7=0\ tai\ 3x^2+x-2=0
x=7
tai
x=\frac{-1\pm\sqrt{1^2+24}}{6}=\frac{-1\pm5}{6}=-1\ tai\ \frac{2}{3}