$$y^4+y^3+4 = 0$$
Answer
$$ \begin{matrix}y_1 = 0.79518+0.96685i & y_2 = 0.79518-0.96685i & y_3 = -1.29518+0.93541i \\[1 em] y_4 = -1.29518-0.93541i & \\[1 em] \end{matrix} $$
Explanation
This polynomial has no rational roots that can be found using Rational Root Test.
Roots were found using quartic formulas
This page was created using
Polynomial Equations Solver