The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.1517\\[1 em]x_2 &= -1.5758+3.6258i\\[1 em]x_3 &= -1.5758-3.6258i \end{aligned} $$Polynomial $ x^3+2x^2+12x-18 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.