The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -1.8089\\[1 em]x_2 &= 1.4045+2.027i\\[1 em]x_3 &= 1.4045-2.027i \end{aligned} $$Polynomial $ x^3-x^2+x+11 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.