Tìm x biết \(\frac{9}{2} - \left[ {\frac{2}{3} - \left( {x + \frac{7}{4}} \right)} \right] = \frac{{ - 5}}{4}\)
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Lời giải:
Báo sai\(\begin{array}{l} \frac{9}{2} - \left[ {\frac{2}{3} - \left( {x + \frac{7}{4}} \right)} \right] = \frac{{ - 5}}{4}\\ \Rightarrow \frac{2}{3} - \left( {x + \frac{7}{4}} \right) = \frac{9}{2} - \frac{{ - 5}}{4}\\ \Rightarrow \frac{2}{3} - \left( {x + \frac{7}{4}} \right) = \frac{9}{2} + \frac{5}{4}\\ \Rightarrow x + \frac{7}{4} = \frac{2}{3} - \left( {\frac{9}{2} + \frac{5}{4}} \right)\\ \Rightarrow x + \frac{7}{4} = \frac{2}{3} - \frac{9}{2} - \frac{5}{4}\\ \Rightarrow x = \frac{2}{3} - \frac{9}{2} - \frac{5}{4} - \frac{7}{4}\\ \Rightarrow x = \frac{8}{{12}} - \frac{{54}}{{12}} - \frac{{15}}{{12}} - \frac{{21}}{{12}}\\ \Rightarrow x = \frac{{8 - 54 - 15 - 21}}{{12}}\\ \Rightarrow x = \frac{{ - 82}}{{12}} = \frac{{ - 41}}{6} \end{array}\)