The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.44\\[1 em]x_2 &= -0.9222\\[1 em]x_3 &= 1.2322 \end{aligned} $$Polynomial $ 4x^3-3x^2-4x+2 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.