$$(2x^3+6x^2+3x-1)(x-3)+2 = 0$$
Answer
$$ \begin{matrix}x_1 = 0.33459 & x_2 = -1.16303 & x_3 = -2.15407 \\[1 em] x_4 = 2.98251 & \\[1 em] \end{matrix} $$
Explanation
$$ \begin{aligned} (2x^3+6x^2+3x-1)(x-3)+2 &= 0&& \text{simplify left side} \\[1 em]2x^4-15x^2-10x+3+2 &= 0&& \\[1 em]2x^4-15x^2-10x+5 &= 0&& \\[1 em] \end{aligned} $$
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