1. Thực hiện phép tính (tính nhanh nếu có thể): a) 5/6 - (1/3 +1/2):20%; 2. Tìm x: a)11/8- 3/8. x = 1/8;
1.
a) \(\frac{5}{6} - \left( {\frac{1}{3} + \frac{1}{2}} \right):20\% \)\( = \frac{5}{6} - \left( {\frac{2}{6} + \frac{3}{6}} \right) \cdot 20\% \)
\( = \frac{5}{6} - \frac{5}{6} \cdot \frac{1}{5}\)\( = \frac{5}{6} - \frac{1}{6}\)\( = \frac{4}{6} = \frac{2}{3}\);
b) \(\frac{3}{{17}}.\frac{6}{{29}} - \frac{3}{{17}}.\frac{{35}}{{29}} + 2022\frac{3}{{17}}\)\( = \frac{3}{{17}} \cdot \left( {\frac{6}{{29}} - \frac{{35}}{{29}}} \right) + 2022\frac{3}{{17}}\)
\( = \frac{3}{{17}} \cdot \left( {\frac{{ - 29}}{{29}}} \right) + 2022\frac{3}{{17}}\)\( = \frac{3}{{17}} \cdot \left( { - 1} \right) + 2022\frac{3}{{17}}\)
\( = \frac{{ - 3}}{{17}} + 2022\frac{3}{{17}} = 2022\).
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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