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