các bạn giúp mình với
a: \(=\dfrac{2\cdot3\cdot4}{4\cdot3\cdot5}=\dfrac{2}{5}\)
b \(=\dfrac{8\cdot9\cdot10}{9\cdot10\cdot11}=\dfrac{8}{11}\)
c: \(=\dfrac{5}{24}\cdot\dfrac{4}{5}\cdot4=\dfrac{16}{24}=\dfrac{2}{3}\)
d: \(=\dfrac{21}{8}\cdot\dfrac{8}{7}\cdot\dfrac{8}{7}\cdot\dfrac{7}{2}=3\cdot4=12\)
\(a).\dfrac{2}{3}\times\dfrac{3}{4}\times\dfrac{4}{5}=\dfrac{6}{12}\times\dfrac{4}{5}=\dfrac{24}{60}=\dfrac{2}{5}\)
\(b).\dfrac{8}{9}\times\dfrac{9}{10}\times\dfrac{10}{11}=\dfrac{72}{90}\times\dfrac{10}{11}=\dfrac{8}{10}\times\dfrac{10}{11}=\dfrac{80}{110}=\dfrac{8}{10}\)
\(c).\dfrac{5}{24}\times\dfrac{12}{15}\times\dfrac{48}{12}=\dfrac{5}{24}\times\dfrac{4}{5}\times4=\dfrac{20}{120}\times4=\dfrac{1}{6}\times4=\dfrac{4}{6}=\dfrac{2}{3}\)
\(d).\dfrac{21}{8}\times\dfrac{16}{14}\times\dfrac{7}{2}\times\dfrac{8}{7}=\dfrac{21}{8}\times\dfrac{8}{7}\times\dfrac{7}{2}\times\dfrac{8}{7}\)
\(=3\times\dfrac{7}{2}\times\dfrac{8}{7}\)
\(=\dfrac{21}{2}\times\dfrac{8}{7}\)
\(=12\)
