$$5x^3+28^2 = 49x$$
Answer
$$ \begin{matrix}x_1 = -5.99592 & x_2 = 2.99796+4.14286i & x_3 = 2.99796-4.14286i \end{matrix} $$
Explanation
$$ \begin{aligned} 5x^3+28^2 &= 49x&& \text{simplify left side} \\[1 em]5x^3+784 &= 49x&& \text{move all terms to the left hand side } \\[1 em]5x^3+784-49x &= 0&& \text{simplify left side} \\[1 em]5x^3-49x+784 &= 0&& \\[1 em] \end{aligned} $$
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