$$4905x^3+981x^5 = 90$$
Answer
$$ \begin{matrix}x_1 = 0.26255 & x_2 = -0.13311+0.2284i & x_3 = -0.13311-0.2284i \\[1 em] x_4 = 0.00183+2.23607i & x_5 = 0.00183-2.23607i \\[1 em] \end{matrix} $$
Explanation
$$ \begin{aligned} 4905x^3+981x^5 &= 90&& \text{simplify left side} \\[1 em]981x^5+4905x^3 &= 90&& \text{move all terms to the left hand side } \\[1 em]981x^5+4905x^3-90 &= 0&& \\[1 em] \end{aligned} $$
This polynomial has no rational roots that can be found using Rational Root Test.
Roots were found using Newton method.
This page was created using
Polynomial Equations Solver