The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.2409\\[1 em]x_2 &= -0.8705+0.8078i\\[1 em]x_3 &= -0.8705-0.8078i \end{aligned} $$Polynomial $ 4x^3+2x^2-3x-7 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.