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\(\left(-2\right).\frac{-38}{21}.\frac{-7}{4}.\frac{\left(-3\right)}{8}=\frac{-2.\left(-38\right).\left(-7\right).\left(-3\right)}{21.4.8}=\frac{4.19.21}{21.4.8}=\frac{19}{8}\)

\(\left(-2\right).\frac{-38}{21}.\frac{-7}{4}.\frac{-3}{8}\)
\(=\left(-2.\frac{-7}{4}.\frac{-3}{8}\right).\frac{-38}{21}\)
\(=\left(\frac{7}{2}.\frac{-3}{8}\right).\frac{-38}{21}\)
\(=\frac{-21}{16}.\frac{-38}{21}\)
\(=\frac{-38}{-16}=\frac{19}{8}\)
\(\left(-2\right).\frac{-38}{21}.\frac{-7}{4}.\left(\frac{-3}{8}\right)\)
\(=\left(-2.\frac{-7}{2}.\frac{-3}{8}\right).\frac{-38}{21}\)
\(=\left(7.\frac{-3}{8}\right).\frac{-38}{21}\)
\(=\frac{-21}{8}.\frac{-38}{21}\)
\(=\frac{-38}{-8}=\frac{19}{4}\)

a, \(\dfrac{-3}{4}.\dfrac{12}{-5}.\left(-\dfrac{25}{6}\right)=\dfrac{9}{5}.\left(-\dfrac{25}{6}\right)=-\dfrac{15}{2}\)
b,\(\left(-2\right).\dfrac{-38}{21}.\dfrac{-7}{4}.\left(-\dfrac{3}{8}\right)=\dfrac{76}{21}.\dfrac{-7}{4}.\left(-\dfrac{3}{8}\right)=-\dfrac{19}{3}.\left(-\dfrac{3}{8}\right)=\dfrac{19}{8}\)
c,\(\left(\dfrac{11}{12}:\dfrac{33}{16}\right).\dfrac{3}{5}=\dfrac{4}{9}.\dfrac{3}{5}=\dfrac{4}{15}\)
d, \(\dfrac{7}{23}.\left[\left(-\dfrac{8}{6}\right)-\dfrac{45}{18}\right]=\dfrac{7}{23}.\left(-\dfrac{13}{6}\right)=-\dfrac{91}{138}\)
like tớ với

Tính:
b) \(-2.\frac{-38}{21}.\frac{-7}{4}.-\frac{3}{8}\)
= \(\frac{\left(-2\right).\left(-38\right).\left(-7\right).\left(-3\right)}{21.4.8}\)
= \(\frac{-1.-19.1}{1.2.4}=\frac{19}{8}\)
// Học tốt!

\(\left(-2\right).\left(\frac{-38}{21}\right).\left(\frac{-7}{4}\right).\left(\frac{3}{-8}\right)\)
\(=\frac{\left(-2\right).\left(-38\right).\left(-7\right).\left(-3\right)}{21.4.8}\)
\(=\frac{19}{8}\)
\(\left(-2\right)\cdot\frac{-38}{21}\cdot\frac{-7}{4}\cdot\left(\frac{-3}{8}\right)\)
\(=\frac{-2\cdot\left(-38\right)\cdot\left(-7\right)\cdot\left(-3\right)}{21\cdot4\cdot8}=\frac{-2\cdot\left(-38\right)\cdot21}{21\cdot4\cdot8}=\frac{-2\cdot\left(-38\right)}{32}=\frac{19}{8}\)

a) \(\frac{3}{4}+\left(-\frac{1}{8}\right)\)
\(=\frac{6}{8}-\frac{1}{8}=\frac{5}{8}\)
b) \(-\frac{5}{12}+\left(-\frac{7}{24}\right)=\left(-\frac{10}{24}\right)+\left(-\frac{7}{24}\right)=-\frac{17}{24}\)
c) \(1+\left(-\frac{7}{8}\right)=\frac{8}{8}-\frac{7}{8}=\frac{1}{8}\)
d) \(\frac{13}{30}-\frac{1}{3}=\frac{13}{30}-\frac{10}{30}=\frac{3}{30}\)
e) \(\frac{4}{21}-\left(-\frac{5}{28}\right)=\frac{4}{21}+\frac{5}{28}=\frac{16}{84}+\frac{15}{84}=\frac{31}{84}\)
\(\left(-2\right)\cdot\frac{-38}{21}\cdot\frac{-7}{4}\cdot\frac{-3}{8}\)
\(=2\cdot\frac{7\cdot3}{21}\cdot\frac{38}{4\cdot8}=2\cdot\frac{38}{2\cdot2\cdot8}=\frac{38}{16}=\frac{19}{8}\)