The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.125\\[1 em]x_2 &= 1.9565\\[1 em]x_3 &= -1.0408+1.7335i\\[1 em]x_4 &= -1.0408-1.7335i \end{aligned} $$Polynomial $ x^4-8x+1 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.