Hãy tìm x biết ​\(\begin{array}{l} \left| {\frac{1}{3} - \frac{1}{5}x} \right| = \frac{2}{5} \end{array}\)

* Hướng dẫn giải

 \(\begin{array}{l} \left| {\frac{1}{3} - \frac{1}{5}x} \right| = \frac{2}{5}\\ \begin{array}{*{20}{l}} {\frac{1}{3} - \frac{1}{5}x = \frac{2}{5}}\,\text{ hoặc }{\frac{1}{3} - \frac{1}{5}x = \frac{{ - 2}}{5}}\\ { - \frac{1}{5}x = \frac{2}{5} - \frac{1}{3} = \frac{1}{{15}}}\text{ hoặc }{ - \frac{1}{5}x = \frac{{ - 2}}{5} - \frac{1}{3} = \frac{{ - 11}}{{15}}}\\ {x = \frac{1}{{15}}:\left( { - \frac{1}{5}} \right) = - \frac{1}{3}}\text{ hoặc }{x = \frac{{ - 11}}{{15}}:\left( { - \frac{1}{5}} \right) = \frac{{11}}{3}} \end{array} \end{array}\)