The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.1539\\[1 em]x_2 &= -2.5279\\[1 em]x_3 &= -0.313+1.3996i\\[1 em]x_4 &= -0.313-1.3996i \end{aligned} $$Polynomial $ x^4+2x^3+x-6 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.