The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.5214\\[1 em]x_2 &= -0.7607+0.8579i\\[1 em]x_3 &= -0.7607-0.8579i \end{aligned} $$Polynomial $ x^3-x-2 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.