The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.3268\\[1 em]x_2 &= 3.5235\\[1 em]x_3 &= -3.8503 \end{aligned} $$Polynomial $ -x^3+x^2+14x-18 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.