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Giải:
B=1,4 .15/49 - (4/5+2/3) :2 1/5
B=7/5.15/49 - 22/15 : 11/5
B=3/7 - 2/3
B=-5/21
Chúc bạn học tốt!
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=1,4 x\(\dfrac{15}{49}-\) \(\left(\dfrac{4}{5}+\dfrac{2}{3}\right)\) : 2\(\dfrac{1}{5}\)
= \(\dfrac{3}{7}\) - \(\dfrac{22}{15}\) : \(\dfrac{11}{5}\)
= \(\dfrac{3}{7}\) - \(\dfrac{2}{3}\)
= \(-\dfrac{5}{21}\)
( 2\(\dfrac{1}{5}\) + \(\dfrac{3}{5}\) \(\times\) \(x\)) = \(\dfrac{3}{4}\)
\(\dfrac{11}{5}\) + \(\dfrac{3}{5}\)\(x\) = \(\dfrac{3}{4}\)
\(\dfrac{3}{5}\)\(x\) = \(\dfrac{3}{4}\) - \(\dfrac{11}{5}\)
\(\dfrac{3}{5}\)\(x\) = - \(\dfrac{29}{20}\)
\(x\) = -\(\dfrac{29}{12}\)
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\(=\dfrac{7}{5}\cdot\dfrac{15}{49}-\left(\dfrac{4}{5}-\dfrac{2}{3}\right):\dfrac{11}{5}\)
\(=\dfrac{3}{7}-\dfrac{2}{15}\cdot\dfrac{5}{11}\)
\(=\dfrac{3}{7}-\dfrac{2}{33}=\dfrac{99-14}{33\cdot7}=\dfrac{85}{231}\)
\(1,4x\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right):2\frac{1}{5}\)
\(=\frac{3}{7}-\frac{22}{15}:2\frac{1}{5}\)
\(=\frac{3}{7}-\frac{2}{3}=-\frac{5}{21}\)
học tốt ~~~
\(1,4\times\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right)\div2\frac{1}{5}\)
\(=\frac{14}{10}\times\frac{15}{49}-\frac{22}{15}\div\frac{11}{5}\)
\(=\frac{7}{5}\times\frac{15}{49}-\frac{22\times5}{15\times11}\)
\(=\frac{7\times15}{5\times49}-\frac{22\times5}{15\times11}\)
\(=\frac{7\times7\times3\times5}{5\times7\times7}-\frac{11\times2\times5}{3\times5\times11}\)
\(=3-\frac{2}{3}\)
\(=\frac{7}{3}\)