$x-3|x+(-3)|=0$
$↔3|x-3|=x$
$↔|x-3|=\dfrac{x}{3}$
\(\leftrightarrow\left[ \begin{array}{l}x-3=\dfrac{x}{3}\\x-3=-\dfrac{x}{3}\end{array} \right.\)
\(\leftrightarrow\left[ \begin{array}{l}3(x-3)=x\\-3(x-3)=x\end{array} \right.\)
\(\leftrightarrow\left[ \begin{array}{l}2x=9\\-4x=-9\end{array} \right.\)
\(\leftrightarrow\left[ \begin{array}{l}x=\dfrac{9}{2}\\x=\dfrac{9}{4}\end{array} \right.\)
