[tex]3x^3-4x^2-13x-6=0\\3x^3-9x^2+5x^2-15x+2x-6=0\\3x^2(x-3)+5x(x-3)+2(x-3)=0\\(3x^2+5x+2)(x-3)=0\\\\x-3=0\\x=3\\\\3x^2+5x+2=0\\3x^2+3x+2x+2=0\\3x(x+1)+2(x+1)=0\\(3x+2)(x+1)=0\\x=-\dfrac{2}{3} \vee x=-1\\\\\\x\in\left\{-1,-\dfrac{2}{3},3\right\}[/tex]
