The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 2.0958\\[1 em]x_2 &= -2.5479+0.4337i\\[1 em]x_3 &= -2.5479-0.4337i \end{aligned} $$Polynomial $ x^3+3x^2-4x-14 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.