Đáp án đúng: B
Giải chi tiết:\(\begin{array}{l}\,\frac{3}{5} - \left| {x - \frac{1}{2}} \right| = 25\% \\\,\,\,\,\,\frac{3}{5} - \left| {x - \frac{1}{2}} \right| = \frac{1}{4}\\\,\,\,\,\,\,\,\,\,\,\,\,\,\left| {x - \frac{1}{2}} \right| = \frac{3}{5} - \frac{1}{4}\\\,\,\,\,\,\,\,\,\,\,\,\,\,\left| {x - \frac{1}{2}} \right| = \frac{7}{{20}}\end{array}\)
TH1: \(x - \frac{1}{2} \ge 0 \Leftrightarrow x \ge \frac{1}{2}\)
\(\begin{array}{l}\left| {x - \frac{1}{2}} \right| = \frac{7}{{20}}\\x - \frac{1}{2} = \frac{7}{{20}}\\x\,\,\,\,\,\,\,\,\,\, = \frac{7}{{20}} + \frac{1}{2}\\x\,\,\,\,\,\,\,\,\,\, = \frac{{17}}{{20}}\,\,\,\,\,\left( {TM} \right)\end{array}\)
TH2: \(x - \frac{1}{2} < 0 \Leftrightarrow x < \frac{1}{2}\)
\(\begin{array}{l}\left| {x - \frac{1}{2}} \right| = \frac{7}{{20}}\\x - \frac{1}{2} = \frac{{ - 7}}{{20}}\\x\,\,\,\,\,\,\,\,\, = \frac{{ - 7}}{{20}} + \frac{1}{2}\\x\,\,\,\,\,\,\,\,\, = \frac{3}{{20}}\,\,\,\left( {TM} \right)\end{array}\)
Vậy \(x = \frac{{17}}{{20}}\) , \(x = \frac{3}{{20}}\)
Chọn B
