The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.2217\\[1 em]x_2 &= -4.5103\\[1 em]x_3 &= -0.634+0.7734i\\[1 em]x_4 &= -0.634-0.7734i \end{aligned} $$Polynomial $ x^4+6x^3+8x^2+6x+1 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.