\[x^{3} = 4x\]
\[x^{3} - 4x = 0\]
\[x\left( x^{2} - 4 \right) = 0\]
\[1)\ x = 0.\]
\[2)\ x^{2} - 4 = 0\]
\[x^{2} = 4\]
\[x = \pm 2.\]
\[Графически:\]
\[y = x^{3};\ \ y = 4x.\]
\[Ответ:x = 0;x = \pm 2.\]