Tìm x biết \(\begin{array}{l} 2\frac{1}{2} - \left( {x + 2} \right) + \frac{4}{5} = \frac{2}{3} - \left( {\frac{{ - 4}}{7}} \right) \end{array}\)
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Lời giải:
Báo sai\(\begin{array}{l} 2\frac{1}{2} - \left( {x + 2} \right) + \frac{4}{5} = \frac{2}{3} - \left( {\frac{{ - 4}}{7}} \right)\\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x + 2 = 2\frac{1}{2} + \frac{4}{5} - \frac{2}{3} - \frac{4}{7}\\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x + 2 = 2 + \left( {\frac{1}{2} + \frac{4}{5}} \right) - \left( {\frac{2}{3} + \frac{4}{7}} \right)\\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x + 2 = 2 + \frac{{13}}{{10}} - \frac{{26}}{{21}}\\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x + 2 = 2 + 1 + \frac{3}{{10}} - 1 - \frac{5}{{21}}\\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x + 2 = 2 + \frac{3}{{10}} - \frac{5}{{21}}\\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = 2 + \frac{3}{{10}} - \frac{5}{{21}} - 2\\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = \frac{{13}}{{210}} \end{array}\)
