Lời giải:
$x^3-9x=0$
$\Leftrightarrow x(x^2-9)=0$
$\Leftrightarrow x(x-3)(x+3)=0$
\(\Leftrightarrow \left[\begin{matrix} x=0\\ x-3=0\\ x+3=0\end{matrix}\right.\Leftrightarrow \left[\begin{matrix} x=0\\ x=3\\ x=-3\end{matrix}\right.\)
\(x^3-9x=0\Leftrightarrow x\left(x^2-9\right)=0\Leftrightarrow x\left(x-3\right)\left(x+3\right)=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x-3=0\\x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=3\\x=-3\end{matrix}\right.\)
Ta có: \(x^3-9x=0\)
\(\Leftrightarrow x\left(x-3\right)\left(x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=3\\x=-3\end{matrix}\right.\)
