The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.3522+0.3906i\\[1 em]x_2 &= -0.3522-0.3906i\\[1 em]x_3 &= -0.4423+0.6693i\\[1 em]x_4 &= -0.4423-0.6693i\\[1 em]x_5 &= 0.5088+0.6403i\\[1 em]x_6 &= 0.5088-0.6403i \end{aligned} $$Polynomial $ 42x^6+24x^5+25x^4+8x^3+21x^2+12x+5 $ has no rational roots that can be found using Rational Root Test, so the roots were found using Newton method.