The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 2.4495i\\[1 em]x_2 &= -2.4495i\\[1 em]x_3 &= 3+2i\\[1 em]x_4 &= 3-2i \end{aligned} $$Polynomial $ x^4-6x^3+19x^2-36x+78 $ has no rational roots that can be found using Rational Root Test, so the roots were found using quartic formulas.