Tìm x biết \(\left| {\frac{{ - 3}}{4}x - 3} \right| = \frac{1}{5}\)
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Lời giải:
Báo sai\(\begin{array}{l} \left| {\frac{{ - 3}}{4}x - 3} \right| = \frac{1}{5}\\ \Rightarrow \frac{{ - 3}}{4}x - 3 = \frac{1}{5}\,\,\,hay\,\,\,\frac{{ - 3}}{4}x - 3 = - \frac{1}{5}\\ \Rightarrow \frac{{ - 3}}{4}x = \frac{1}{5} + 3\,\,\,hay\,\,\frac{{ - 3}}{4}x = - \frac{1}{5} + 3\\ \Rightarrow \frac{{ - 3}}{4}x = \frac{{16}}{5}\,\,\,\,\,hay\,\,\,\,\frac{{ - 3}}{4}x = \frac{{14}}{5}\\ \Rightarrow x = \frac{{16}}{5}:\frac{{ - 3}}{4}\,\,\,\,\,hay\,\,\,\,x = \frac{{14}}{5}:\frac{{ - 3}}{4}\\ \Rightarrow x = \frac{{16}}{5}.\frac{4}{{ - 3}}\,\,\,\,\,hay\,\,\,\,x = \frac{{14}}{5}.\frac{4}{{ - 3}}\\ \Rightarrow x = \frac{{ - 64}}{{15}}\,\,\,\,\,hay\,\,\,\,x = \frac{{ - 56}}{{15}} \end{array}\)