Đáp án:
Giải thích các bước giải:
\(\begin{array}{l} + )\,\,\left| x \right| \times \frac{2}{7} = \frac{8}{9}\\ \Leftrightarrow \left| x \right| = \frac{8}{9}.\frac{7}{2}\\ \Leftrightarrow \left| x \right| = \frac{{28}}{9}\,\,\,\,\left( * \right)\\ \Leftrightarrow x = \frac{{28}}{9}\,\,\,\,\,hoac\,\,\,\,x = \frac{{ - 28}}{9}\end{array}\)
\(\begin{array}{l} + )\,\,\left| x \right| = 2,7\\x\,\, = \,\,2,7\,\,\,\,hoac\,\,\,x = - 2,7\end{array}\)
