The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -1.1449\\[1 em]x_2 &= -1.8625\\[1 em]x_3 &= 15.0074 \end{aligned} $$Polynomial $ x^3-12x^2-43x-32 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.