The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.5437\\[1 em]x_2 &= -0.7718+1.1151i\\[1 em]x_3 &= -0.7718-1.1151i \end{aligned} $$Polynomial $ x^3+x^2+x-1 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.