5b. \(\left(\dfrac{-5}{28}+1,75+\dfrac{8}{35}\right):\left(-3\dfrac{9}{20}\right)\)
\(=\left(\dfrac{-5}{28}+\dfrac{7}{4}+\dfrac{8}{35}\right):\left(-3\dfrac{9}{20}\right)\)
\(=\left(\dfrac{11}{7}+\dfrac{8}{35}\right):\left(-3\dfrac{9}{20}\right)\)
\(=\dfrac{9}{5}:\left(-3\dfrac{9}{20}\right)\)
\(=\dfrac{9}{5}:\dfrac{-69}{20}\)
\(=\dfrac{-12}{23}\)
6d.\(\left(\dfrac{7}{8}-\dfrac{3}{4}\right).1\dfrac{1}{3}-\dfrac{2}{7}.\left(3.5\right)^2\)
\(=\dfrac{1}{8}.1\dfrac{1}{3}-\dfrac{2}{7}.\left(3.5\right)^2\)
\(=\dfrac{1}{8}.1\dfrac{1}{3}-\dfrac{2}{7}.225\)
\(=\dfrac{1}{8}.\dfrac{4}{3}-\dfrac{2}{7}.225\)
\(=\dfrac{1}{6}-\dfrac{2}{7}.225\)
\(=\dfrac{1}{6}-\dfrac{450}{7}\)
\(=\dfrac{-2693}{42}\)
6e. \(\left(\dfrac{3}{5}+0,415-\dfrac{3}{200}\right)2\dfrac{2}{3}.0,25\)
\(=\left(\dfrac{3}{5}+\dfrac{83}{200}-\dfrac{3}{200}\right)2\dfrac{2}{3}.0,25\)
\(=\left(\dfrac{3}{5}+\dfrac{2}{5}\right)2\dfrac{2}{3}.0,25\)
\(=1.2\dfrac{2}{3}.0,25\)
\(=\dfrac{8}{3}.\dfrac{1}{4}\)
\(=\dfrac{2}{3}\)
Bài 5:
b)\(\left(\dfrac{-5}{28}+1,75+\dfrac{8}{35}\right):\left(-3\dfrac{9}{20}\right)\)
=\(\left(\dfrac{-5}{28}+\dfrac{175}{100}+\dfrac{8}{35}\right):\dfrac{-69}{20}\)
=\(\left(\dfrac{-5}{28}+\dfrac{7}{4}+\dfrac{8}{35}\right):\dfrac{-69}{20}\)
=\(\left(\dfrac{-5}{28}+\dfrac{49}{28}+\dfrac{8}{35}\right):\dfrac{-69}{20}\)
=\(\left(\dfrac{11}{7}+\dfrac{8}{35}\right):\dfrac{-69}{20}\)
\(\left(\dfrac{55}{35}+\dfrac{8}{35}\right):\dfrac{-69}{20}\)
=\(\dfrac{9}{5}:\dfrac{-69}{20}\)
=\(\dfrac{9}{5}.\dfrac{-20}{69}\)
=\(\dfrac{-12}{23}\)
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