$$x^3+7^2x-40 = 0$$
Answer
$$ \begin{matrix}x_1 = 0.80565 & x_2 = -0.40283+7.03469i & x_3 = -0.40283-7.03469i \end{matrix} $$
Explanation
$$ \begin{aligned} x^3+7^2x-40 &= 0&& \text{simplify left side} \\[1 em]x^3+49x-40 &= 0&& \\[1 em] \end{aligned} $$
This polynomial has no rational roots that can be found using Rational Root Test.
Roots were found using qubic formulas.
This page was created using
Polynomial Equations Solver