The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -1.3247\\[1 em]x_2 &= 0.6624+0.5623i\\[1 em]x_3 &= 0.6624-0.5623i \end{aligned} $$Polynomial $ -x^3+x-1 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.