The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.5752\\[1 em]x_2 &= 0.6422\\[1 em]x_3 &= 0.3149+0.6046i\\[1 em]x_4 &= 0.3149-0.6046i\\[1 em]x_5 &= -0.3723+0.5204i\\[1 em]x_6 &= -0.3723-0.5204i\\[1 em]x_7 &= -1.7261+6.8431i\\[1 em]x_8 &= -1.7261-6.8431i \end{aligned} $$Polynomial $ 2x^8+7x^7+100x^6+5x^5+3x^4+2x^3+3x^2-5x-7 $ has no rational roots that can be found using Rational Root Test, so the roots were found using Newton method.