The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.9188\\[1 em]x_2 &= 0.818\\[1 em]x_3 &= 0.4983+0.8798i\\[1 em]x_4 &= 0.4983-0.8798i\\[1 em]x_5 &= -0.5664+1.0711i\\[1 em]x_6 &= -0.5664-1.0711i\\[1 em]x_7 &= -1.6315+0.6643i\\[1 em]x_8 &= -1.6315-0.6643i \end{aligned} $$Polynomial $ 2x^8+7x^7+9x^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.