The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.0596\\[1 em]x_2 &= -2.6887\\[1 em]x_3 &= -0.464+0.3532i\\[1 em]x_4 &= -0.464-0.3532i\\[1 em]x_5 &= 0.4096+0.5188i\\[1 em]x_6 &= 0.4096-0.5188i \end{aligned} $$Polynomial $ 42x^6+120x^5+20x^4+8x^3+21x^2+18x+1 $ has no rational roots that can be found using Rational Root Test, so the roots were found using Newton method.