358. Solve the equation:

$$
\begin{aligned}
& 5 x-5 x^{3}+x^{5}=0 . \\
& \text { Problems by S. Stevin. }
\end{aligned}
$$
358. $x^{4}-5 x^{2}+5=0$

$$
x= \pm \sqrt{\frac{5 \pm \sqrt{5}}{2}}
$$

Stevin Simon (1548-1620), a Dutch engineer who can justly be considered the inventor of decimal fractions (treatise "La Disme", 1585).