The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.7776\\[1 em]x_2 &= -0.8505\\[1 em]x_3 &= 1.5488\\[1 em]x_4 &= -0.7379+1.1866i\\[1 em]x_5 &= -0.7379-1.1866i \end{aligned} $$Polynomial $ x^5-x^3-3x^2+2 $ has no rational roots that can be found using Rational Root Test, so the roots were found using Newton method.