The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.0596\\[1 em]x_2 &= -0.5962\\[1 em]x_3 &= -0.354+0.7957i\\[1 em]x_4 &= -0.354-0.7957i\\[1 em]x_5 &= 0.6105+0.7144i\\[1 em]x_6 &= 0.6105-0.7144i \end{aligned} $$Polynomial $ 42x^6+6x^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.