\[5x^{3} - 125x = 0\]
\[5x\left( x^{2} - 25 \right) = 0\]
\[1)\ 5x = 0\]
\[x = 0.\]
\[2)\ x^{2} - 25 = 0\]
\[x^{2} = 25\]
\[x = \pm 5.\]
\[Ответ:x = 0;x = \pm 5.\]