Tìm x biết: \({x^3} - 4x = 0\).

\({x^3} - 4x = 0 \Leftrightarrow x\left( {{x^2} - 4} \right) = 0\)

\( \Leftrightarrow x\left( {x - 2} \right)\left( {x + 2} \right) = 0 \Leftrightarrow \left[ {\begin{array}{*{20}{c}}{x = 0}\\{x = 2}\\{x = - 2}\end{array}} \right.\).