The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.5+0.866i\\[1 em]x_2 &= 0.5-0.866i\\[1 em]x_3 &= 1+2i\\[1 em]x_4 &= 1-2i \end{aligned} $$Polynomial $ x^4-3x^3+8x^2-7x+5 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.