Tìm x biết: x³ – 2x = 0.

\[\begin{array}{l}{x^3} - 2x = 0\\ \Leftrightarrow x\left( {{x^2} - 2} \right) = 0\\ \Leftrightarrow \left[ \begin{array}{l}x = 0\\{x^2} = 2\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}x = 0\\x = 2\\x = - 2\end{array} \right.\end{array}\]