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A=\(\frac{2}{1}\cdot3+\frac{2}{3}\cdot5+\frac{2}{5}\cdot7+\frac{2}{7}\cdot9\)
A=\(\frac{3}{1}\cdot2+\frac{5}{3}\cdot2+\frac{7}{5}\cdot2+\frac{9}{7}\cdot2\)
A=\(2\cdot\left(3+\frac{5}{3}+\frac{7}{5}+\frac{9}{7}\right)\)
A=\(2\cdot\frac{772}{105}\)
A=\(\frac{1544}{105}\)
A=\(14\frac{74}{105}\)
\(5\dfrac{3}{4}:3+2\dfrac{1}{4}\times\dfrac{1}{3}-\dfrac{1}{8}=\left(5\dfrac{3}{4}+2\dfrac{1}{4}\right)\times\dfrac{1}{3}-\dfrac{1}{8}\\ =8\times\dfrac{1}{3}-\dfrac{1}{8}=\dfrac{8}{3}-\dfrac{1}{8}=\dfrac{61}{24}\\ ----\\ \dfrac{3}{5}:\dfrac{5}{6}:\dfrac{6}{7}:\dfrac{7}{8}+\dfrac{2}{5}+\dfrac{23}{35}\\ =\dfrac{3}{5}\times\dfrac{6}{5}\times\dfrac{7}{6}\times\dfrac{8}{7}+\dfrac{2}{5}+\dfrac{23}{35}=\dfrac{18}{25}\times\dfrac{4}{3}+\dfrac{2}{5}+\dfrac{23}{35}=\dfrac{353}{175}\)
\(\frac{1}{7}\cdot\frac{2}{3}+\frac{5}{6}:\frac{3}{10}-\frac{2}{3}\cdot\frac{3}{7}\)
\(=\left(\frac{1}{7}\cdot\frac{2}{3}-\frac{2}{3}\cdot\frac{3}{7}\right)+\frac{5}{6}\cdot\frac{10}{3}\)
\(=\frac{2}{3}\cdot\left(-\frac{2}{7}\right)+\frac{5}{3}\cdot\frac{5}{3}\)
\(=-\frac{4}{21}+\frac{25}{6}=\frac{167}{42}\)
Xin lỗi không nhanh được
\(\frac{4}{5}x\frac{1}{4}+\frac{1}{2}x\frac{4}{5}\)
\(\frac{4}{5}x\left(\frac{1}{4}+\frac{1}{2}\right)\)
\(\frac{4}{5}x\frac{3}{4}=\frac{3}{5}\)
\(\frac{3}{4}x\frac{4}{5}+\frac{5}{6}x\frac{6}{7}x\frac{7}{8}\)
\(\frac{3}{5}+\frac{5}{8}=\frac{49}{40}\)
A) 4/5 x 1/4 + 1/2 x 4/5
= 4/5 x (1/4 + 1/2)
= 4/5 x (1/4 + 2/4)
= 4/5 x 3/4
= 3/5
2/7×11/5+3/5+2/7
=2/7(11/5+3/5)
=2/7×14/5
=28/35
=4/5
Tích nhé.○w○