1. Thực hiện phép tính (tính nhanh nếu có thể): a) (- 1/6 + 5/ - 12) + 7/12; 2. Tìm \[x\]: a) 11/8- 3/8.x =1/8;
1.
a) \[\left( {\frac{{ - 1}}{6} + \frac{5}{{ - 12}}} \right) + \frac{7}{{12}}\]\[ = \frac{{ - 1}}{6} + \left( {\frac{5}{{ - 12}} + \frac{7}{{12}}} \right)\]
\[ = \frac{{ - 1}}{6} + \left( {\frac{{ - 5}}{{12}} + \frac{7}{{12}}} \right)\]\[ = \frac{{ - 1}}{6} + \frac{2}{{12}}\]\[ = \frac{{ - 1}}{6} + \frac{1}{6} = 0\];
b) \[\frac{7}{{36}} - \frac{8}{{ - 9}} + \frac{{ - 2}}{3}\]\[ = \frac{7}{{36}} + \frac{8}{9} + \frac{{ - 2}}{3}\]
\[ = \frac{7}{{36}} + \frac{{32}}{{36}} + \frac{{ - 24}}{{36}}\]\( = \frac{{15}}{{36}} = \frac{5}{{12}}\).
2.
a) \[\frac{{11}}{8} - \frac{3}{8} \cdot x = \frac{1}{8}\] \[\frac{3}{8} \cdot x = \frac{{11}}{8} - \frac{1}{8}\] \[\frac{3}{8} \cdot x = \frac{{10}}{8}\] \[x = \frac{{10}}{8}:\frac{3}{8}\] \[x = \frac{{10}}{3}\]. Vậy \[x = \frac{{10}}{3}\]. | b) \({\left( {x - \frac{1}{2}} \right)^2} = \frac{1}{4}\)
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