The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.6608\\[1 em]x_2 &= -1.3304+1.9103i\\[1 em]x_3 &= -1.3304-1.9103i \end{aligned} $$Polynomial $ x^3+x^2+x-9 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.