The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.4397\\[1 em]x_2 &= -0.1449+0.4543i\\[1 em]x_3 &= -0.1449-0.4543i \end{aligned} $$Polynomial $ 20x^3-3x^2+2x-2 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.