The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.8953\\[1 em]x_2 &= -4.0422\\[1 em]x_3 &= -0.4265+1.3238i\\[1 em]x_4 &= -0.4265-1.3238i \end{aligned} $$Polynomial $ x^4+4x^3+x^2+3x-7 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.