The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.4782\\[1 em]x_2 &= -12.1849\\[1 em]x_3 &= -0.6467+0.518i\\[1 em]x_4 &= -0.6467-0.518i \end{aligned} $$Polynomial $ 2x^4+26x^3+20x^2+x-8 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.