\[3|x| - 1 = 0\]
\[3|x| = 1\]
\[|x| = \frac{1}{3}\]
\[x = \frac{1}{3}\ \ \ или\ \ \ \ x = - \frac{1}{3}\]
\[Ответ:\frac{1}{3};\ - \frac{1}{3}.\]