The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.459\\[1 em]x_2 &= -0.6045+0.3855i\\[1 em]x_3 &= -0.6045-0.3855i \end{aligned} $$Polynomial $ 4x^3-x^2-5x-3 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.