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\(a.\frac{1}{7}\times\frac{-3}{8}+\frac{-13}{8}==\frac{-3}{56}+\frac{-13}{8}=\frac{-3}{56}+\frac{-91}{56}=\frac{-94}{56}=\frac{-47}{28}\)
\(b.\frac{3}{5}\times\frac{13}{40}-\frac{1}{10}\times\frac{16}{23}=\frac{39}{200}-\frac{8}{115}=\frac{577}{4600}\)
\(c.\left(\frac{-3}{4}+\frac{2}{5}\right):\frac{3}{7}+\left(\frac{3}{5}+\frac{1}{4}\right):\frac{3}{7}\)
\(=\left(\frac{-3}{4}+\frac{2}{5}\right)\times\frac{7}{3}+\left(\frac{3}{5}+\frac{1}{4}\right)\times\frac{7}{3}\)
\(=\frac{7}{3}\times\left(\frac{-3}{4}+\frac{2}{5}+\frac{3}{5}+\frac{1}{4}\right)\)
\(=\frac{7}{3}\times\left[\left(\frac{-3}{4}+\frac{1}{4}\right)+\left(\frac{2}{5}+\frac{3}{5}\right)\right]\)
\(=\frac{7}{3}\times\left(\frac{-2}{4}+1\right)\)
\(=\frac{7}{3}\times\frac{1}{2}\)
\(=\frac{7}{6}\)
\(d.\frac{7}{8}:\left(\frac{2}{9}-\frac{1}{8}\right)+\frac{7}{8}:\left(\frac{1}{6}-\frac{5}{12}\right)\)
\(=\frac{7}{8}:\frac{7}{72}+\frac{7}{8}:\left(\frac{-1}{4}\right)\)
\(=\frac{7}{8}\times\frac{72}{7}+\frac{7}{8}\times-4\)
\(=\frac{7}{8}\times\left(\frac{72}{7}+\left(-4\right)\right)\)
\(=\frac{7}{8}\times\frac{44}{7}\)
\(=\frac{11}{2}\)
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A= 7/8:(4/18-1/18)+7/8:(1/36-15/36)
=7/8:1/6+7/8:(-7/18)
=7/8:(1/6+-7/18)=7/8:(3/18+-7/18)=7/8:(-2/9)=-63/18=-7/2
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\(\frac{2}{7}+\frac{-3}{8}+\frac{11}{7}+\frac{1}{3}+\frac{1}{7}+\frac{5}{-8}\)
= \(\frac{2}{7}+\frac{-3}{8}+\frac{11}{7}+\frac{1}{3}+\frac{1}{7}+\frac{-5}{8}\)
= \(\left(\frac{2}{7}+\frac{11}{7}\right)+\left(\frac{-3}{8}+\frac{-5}{8}\right)+\left(\frac{1}{7}+\frac{1}{3}\right)\)
= \(\frac{13}{7}+-1+\frac{10}{21}\)
= \(\frac{39}{21}+\frac{-21}{21}+\frac{10}{21}\)
= \(\frac{28}{21}\)
= \(\frac{4}{3}\)
\(\frac{2}{7}+\frac{-3}{8}+\frac{11}{7}+\frac{1}{3}+\frac{1}{7}+\frac{-5}{8}\)
\(\Rightarrow\left(\frac{2}{7}+\frac{11}{7}+\frac{1}{7}\right)+\left(\frac{-3}{8}+\frac{-5}{8}\right)+\frac{1}{3}\)
\(\Rightarrow\frac{14}{7}+\frac{-8}{8}+\frac{1}{3}\)
\(\Rightarrow2+\left(-1\right)+\frac{1}{3}\)
\(\Rightarrow1+\frac{1}{3}\)
\(\Rightarrow\frac{4}{3}\)
chúc bạn học giỏi ! ^_^
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B = ( 7\(\frac{1}{3}\) + 8\(\frac{1}{5}\) ) - ( 7\(\frac{1}{5}\) + 8\(\frac{1}{7}\) - 3\(\frac{1}{4}\) )
B = ( \(\frac{22}{3}\) + \(\frac{41}{5}\)) - ( \(\frac{36}{5}\) + \(\frac{57}{7}\) - \(\frac{13}{4}\) )
B = \(\frac{233}{15}\) - \(\frac{1693}{140}\)
B = \(\frac{289}{84}\)
\(\left(-7\right)+\left(-7\right).1+986.8.124+8\\ =\left(-7\right)+\left(-7\right)+7888.124+8\\ =\left(-7\right)+\left(-7\right)+978112+8\\ =978106\)
=[(-7)+(-7)].1+986.8.124+8.1
=-14.1+986.8.(124+1)+8
=14+986.8.125+8
=(14+986).8.125+8
=1000.1000+8
=1000000+8
=1000008