The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.4116+0.5467i\\[1 em]x_2 &= 0.4116-0.5467i\\[1 em]x_3 &= -1.9116+2.6504i\\[1 em]x_4 &= -1.9116-2.6504i \end{aligned} $$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.