The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.6768\\[1 em]x_2 &= -0.7388\\[1 em]x_3 &= 1.7137\\[1 em]x_4 &= -0.8258+1.2854i\\[1 em]x_5 &= -0.8258-1.2854i \end{aligned} $$Polynomial $ -x^5+x^3+4x^2-2 $ has no rational roots that can be found using Rational Root Test, so the roots were found using Newton method.