The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -1.4191\\[1 em]x_2 &= -9.969\\[1 em]x_3 &= 0.194+1.1112i\\[1 em]x_4 &= 0.194-1.1112i \end{aligned} $$Polynomial $ x^4+11x^3+11x^2+9x+18 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.