\(\frac{2}{3}+\left(\frac{5}{7}+\frac{-2}{3}\right)\)

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15 tháng 4 2019

\(\frac{2}{3}+\left(\frac{5}{7}+\frac{-2}{3}\right)\)

\(=\left(\frac{2}{3}+\frac{-2}{3}\right)+\frac{5}{7}\)

\(=0+\frac{5}{7}\)

\(=\frac{5}{7}\)

15 tháng 4 2019

\(\frac{2}{3}+\left(\frac{5}{7}+\frac{-2}{3}\right)\)

\(=\frac{2}{3}+\frac{5}{7}+\frac{-2}{3}\)

\(=\left(\frac{2}{3}+\frac{-2}{3}\right)+\frac{5}{7}\)

\(=0+\frac{5}{7}=\frac{5}{7}\)

~Học tốt~

13 tháng 7 2016

\(\left(\frac{2}{3}\right)^{21}\cdot\left(\frac{3}{2}\right)^{19}=\left(\frac{2}{3}\right)^{21}\cdot\left(\frac{2}{3}\right)^{-19}=\left(\frac{2}{3}\right)^2\)

\(\left(\frac{2}{5}\right)^3\cdot\left(\frac{5}{4}\right)^2=\frac{2^3}{5^3}\cdot\frac{5^2}{4^2}=\frac{4\cdot2}{5^2\cdot5}\cdot\frac{5^2}{4^2}=\frac{2}{20}=\frac{1}{10}\)

\(\left(\frac{5}{3}\right)^{27}\cdot\left(\frac{3}{5}\right)^{30}=\left(\frac{3}{5}\right)^{-27}\cdot\left(\frac{3}{5}\right)^{30}=\left(\frac{3}{5}\right)^3\)

câu cuối tương tự như câu 3

12 tháng 7 2016

AI HỘ MÌNH VỚI Ạ

22 tháng 8 2019

1,\(\frac{2}{9}.\left(x-\frac{9}{4}\right)+\frac{1}{2}=\frac{3}{7}.\left(7-\frac{1}{6}\right)+\frac{1}{3}\)

  \(\frac{2}{9}.\left(x-\frac{9}{4}\right)+\frac{1}{2}=\frac{3}{7}.\frac{41}{6}+\frac{1}{3}\)

\(\frac{2}{9}.\left(x-\frac{9}{4}\right)+\frac{1}{2}=\frac{41}{14}+\frac{1}{3}\)

 \(\frac{2}{9}.\left(x-\frac{9}{4}\right)+\frac{1}{2}=\frac{137}{42}\)

\(\frac{2}{9}.\left(x-\frac{9}{4}\right)=\frac{137}{42}-\frac{1}{2}\)

\(\frac{2}{9}.\left(x-\frac{9}{4}\right)=\frac{58}{21}\)

 \(\left(x-\frac{9}{4}\right)=\frac{5}{2}:\frac{2}{9}\)

\(\left(x-\frac{9}{4}\right)=\frac{45}{4}\)

\(x=\frac{45}{4}+\frac{9}{4}\)

\(x=\frac{27}{2}\)

22 tháng 8 2019

Bước cưối 58/21 minh man viết nhầm nên sai 

29 tháng 5 2019

a) \(\left(\frac{-3}{4}+\frac{2}{5}\right):\frac{3}{7}+\left(\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)

\(\left(-\frac{3}{4}+\frac{2}{5}+\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)

\(0:\frac{3}{7}\)

\(0\)

29 tháng 5 2019

b) \(\frac{2}{8}:\left(\frac{2}{9}-\frac{1}{18}\right)+\frac{7}{8}:\left(\frac{1}{36}-\frac{5}{12}\right)\)

\(\frac{1}{4}:\frac{1}{6}+\frac{7}{8}:\frac{-7}{18}\)

=\(\frac{1}{4}.6+\frac{7}{8}.\frac{-18}{7}\)

\(\frac{3}{2}-\frac{3}{4}\)

\(\frac{3}{4}\)

15 tháng 7 2017

a) \(\left(\frac{-3}{2}+\frac{2}{5}\right):\frac{3}{7}+\left(\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)

\(\left(\frac{-3}{2}+\frac{2}{5}+\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)

\(\frac{-3}{4}:\frac{3}{7}\)

\(\frac{-7}{4}\)

b) \(\frac{7}{8}:\left(\frac{2}{9}-\frac{1}{18}\right)+\frac{7}{8}:\left(\frac{1}{36}-\frac{5}{12}\right)\)

\(=\frac{7}{8}:\frac{1}{6}+\frac{7}{8}:\left(\frac{-7}{18}\right)\)

\(=\frac{7}{8}.6+\frac{7}{8}.\left(\frac{-18}{7}\right)\)

\(=\frac{7}{8}.\left(6+\frac{-18}{7}\right)\)

\(=\frac{7}{8}.\frac{24}{7}\)

\(=3\)

30 tháng 4 2019

\(\left(\frac{3}{8}+-\frac{3}{4}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)

\(=\left(\frac{9}{24}+-\frac{18}{24}+\frac{14}{24}\right):\frac{5}{6}+\frac{1}{2}\)

\(=\frac{5}{24}:\frac{5}{6}+\frac{1}{2}\)

\(=\frac{5}{24}.\frac{6}{5}+\frac{1}{2}\)

\(=\frac{1}{4}+\frac{1}{2}\)

\(=\frac{1}{4}+\frac{2}{4}\)

\(=\frac{3}{4}\)

30 tháng 4 2019

\(\frac{1}{2}+\frac{3}{4}-\left(\frac{3}{4}-\frac{4}{5}\right)\)

\(=\frac{1}{2}+\frac{3}{4}-\left(\frac{15}{20}-\frac{16}{20}\right)\)

\(=\frac{1}{2}+\frac{3}{4}-\frac{-1}{20}\)

\(=\frac{10}{20}+\frac{15}{20}-\frac{-1}{20}\)

\(=\frac{25}{20}-\frac{-1}{20}\)

\(=\frac{26}{20}\)

\(=\frac{13}{10}\)