The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.7867\\[1 em]x_2 &= 0.1524+0.6152i\\[1 em]x_3 &= 0.1524-0.6152i\\[1 em]x_4 &= -0.4757+0.8834i\\[1 em]x_5 &= -0.4757-0.8834i\\[1 em]x_6 &= 0.8833+0.8896i\\[1 em]x_7 &= 0.8833-0.8896i \end{aligned} $$Polynomial $ 6x^7-2x^6+4x^5+2x^4+8x^3+6x^2+x+3 $ has no rational roots that can be found using Rational Root Test, so the roots were found using Newton method.