The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.4628\\[1 em]x_2 &= -0.548\\[1 em]x_3 &= -5.9149 \end{aligned} $$Polynomial $ -4x^3-24x^2-x+6 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.