The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.8574\\[1 em]x_2 &= 0.3037+0.2314i\\[1 em]x_3 &= 0.3037-0.2314i \end{aligned} $$Polynomial $ 8x^3+2x^2-3x+1 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.