The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.1558\\[1 em]x_2 &= 1.2413\\[1 em]x_3 &= -2.5855 \end{aligned} $$Polynomial $ 2x^3+3x^2-6x-1 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.