1) Thực hiện phép tính:
a) \(\frac{1}{4} + \frac{3}{4} \cdot \left( {\frac{2}{3} - 0,5} \right)\)
b) \(1\frac{3}{{25}} - \frac{{17}}{{19}} - \frac{3}{{25}} + \frac{{2022}}{{2023}} - \frac{2}{{19}}\)
2) Tìm \(x\) biết:
a) \(\frac{2}{3}x - \frac{1}{2} = \frac{1}{{10}}\)
b) \(5,16 - 2x = (5,7 + 2,3) \cdot ( - 0,3)\)
Áp dụng quy tắc cộng, trừ, nhân, chia.
1)
a) \(\frac{1}{4} + \frac{3}{4} \cdot \left( {\frac{2}{3} - 0,5} \right)\)\( = \frac{1}{4} + \frac{3}{4} \cdot \left( {\frac{2}{3} - \frac{1}{2}} \right)\)\( = \frac{1}{4} + \frac{3}{4} \cdot \frac{1}{6}\)\( = \frac{1}{4} + \frac{1}{8}\)\( = \frac{3}{8}\)
b) \(1\frac{3}{{25}} - \frac{{17}}{{19}} - \frac{3}{{25}} + \frac{{2022}}{{2023}} - \frac{2}{{19}}\)\( = \left( {1\frac{3}{{25}} - \frac{3}{{25}}} \right) + \left( {\frac{{ - 17}}{{19}} + \frac{{ - 2}}{{19}}} \right) + \frac{{2022}}{{2023}}\) \( = 1 + ( - 1) + \frac{{2022}}{{2023}}\) \( = \frac{{2022}}{{2023}}.\)
2)
a) \(\frac{2}{3}x - \frac{1}{2} = \frac{1}{{10}}\)
\(\frac{2}{3}x = \frac{1}{{10}} + \frac{1}{2}\)
\(\frac{2}{3}x = \frac{3}{5}\)
\(x = \frac{3}{5}:\frac{2}{3}\)
\(x = \frac{3}{5}.\frac{3}{2}\)
\(x = \frac{9}{{10}}\)
Vậy \(x = \frac{9}{{10}}\).
b) \(5,16 - 2x = (5,7 + 2,3) \cdot ( - 0,3)\)
\(5,16 - 2x = - 2,4\)
\(2x = 5,16 - ( - 2,4)\)
\(2x = 7,56\)
\(x = 7,56:2\)
\(x = 3,78\)
Vậy \(x = 3,78\)
