Ôn tập toán 6

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a,\(\dfrac{2}{3}-\dfrac{3}{5}\div\left(-1\dfrac{1}{5}\right)+\left(\dfrac{-2}{3}\right)\times\dfrac{3}{8}\)

b,\(17\dfrac{11}{9}-\left(6\dfrac{3}{13}+7\dfrac{11}{19}\right)+\left(10\dfrac{3}{13}-5\dfrac{1}{4}\right)\)

c,\(\left(\dfrac{-3}{2}\right)^2-\left[-2\dfrac{1}{3}-\left(\dfrac{3}{4}+\dfrac{1}{3}\right)\div2\dfrac{3}{5}\right]\times\left(\dfrac{-3}{4}\right)\)

d,\(\dfrac{21}{33}\div\dfrac{11}{5}-\dfrac{13}{33}\div\dfrac{11}{5}+\dfrac{25}{33}\div\dfrac{11}{5}+\dfrac{6}{11}\)

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Nguyễn Yến Nhi
12 tháng 8 2017 lúc 10:02

a)\(\dfrac{2}{3}-\dfrac{3}{5}:\left(-1\dfrac{1}{5}\right)+\left(\dfrac{-2}{3}\right)\cdot\dfrac{3}{8}\)

\(=\dfrac{2}{3}-\dfrac{3}{5}\cdot\dfrac{-5}{6}+\left(\dfrac{-1}{4}\right)=\dfrac{5}{12}+\dfrac{1}{2}=\dfrac{11}{12}\)

b)\(17\dfrac{11}{9}-\left(6\dfrac{3}{13}+7\dfrac{11}{19}\right)+\left(10\dfrac{3}{13}-5\dfrac{1}{4}\right)=\dfrac{164}{9}-\left(\dfrac{81}{13}+\dfrac{144}{19}\right)+\left(\dfrac{133}{13}-\dfrac{21}{4}\right)=\dfrac{164}{9}-\dfrac{3411}{247}+\dfrac{259}{52}=\dfrac{6425}{684}\)

c)\(\left(\dfrac{-3}{2}\right)^2-\left[-2\dfrac{1}{3}-\left(\dfrac{3}{4}+\dfrac{1}{3}\right):2\dfrac{3}{5}\right]\cdot\left(\dfrac{-3}{4}\right)=\dfrac{9}{4}-\left[\dfrac{-7}{3}-\dfrac{13}{12}\cdot\dfrac{5}{13}\right]\cdot\left(\dfrac{-3}{4}\right)=\dfrac{9}{4}-\left(\dfrac{-11}{4}\right)\cdot\left(\dfrac{-3}{4}\right)=\dfrac{3}{16}\)

d)\(\dfrac{21}{33}:\dfrac{11}{5}-\dfrac{13}{33}:\dfrac{11}{5}+\dfrac{25}{33}:\dfrac{11}{5}+\dfrac{6}{11}=\dfrac{5}{11}\cdot\left(\dfrac{21}{33}-\dfrac{13}{33}+\dfrac{25}{33}\right)+\dfrac{6}{11}=\dfrac{5}{11}\cdot1+\dfrac{6}{11}=1\)

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Hải Đăng
12 tháng 8 2017 lúc 9:18

\(a)\dfrac{2}{3}-\dfrac{3}{5}:\left(-1\dfrac{1}{5}\right)+\left(\dfrac{-2}{3}\right).\dfrac{3}{8}\)

\(=\dfrac{2}{3}-\dfrac{3}{5}:\left(\dfrac{-6}{5}\right)+\left(\dfrac{-2}{3}\right).\dfrac{3}{8}\)

\(=\dfrac{2}{3}-\dfrac{-1}{2}+\left(\dfrac{-2}{3}\right).\dfrac{3}{8}\)

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

\(=\dfrac{7}{6}+\dfrac{-1}{4}\)

\(=\dfrac{11}{12}\)

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Hải Đăng
12 tháng 8 2017 lúc 9:42

\(b)17\dfrac{11}{9}-\left(6\dfrac{3}{13}+7\dfrac{11}{19}\right)+\left(10\dfrac{3}{13}-5\dfrac{1}{4}\right)\)

\(=\dfrac{164}{9}-\left(\dfrac{81}{13}-\dfrac{144}{19}\right)+\left(\dfrac{133}{13}-\dfrac{21}{4}\right)\)

\(=\dfrac{164}{9}-\dfrac{-333}{247}+\dfrac{259}{52}\)

\(=19,57040036+\dfrac{259}{52}\)

\(=24,55116959\)

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Hải Đăng
12 tháng 8 2017 lúc 10:01

\(c)\left(\dfrac{-3}{3}\right)^2-\left[-2\dfrac{1}{3}-\left(\dfrac{3}{4}+\dfrac{1}{3}\right):2\dfrac{3}{5}\right].\left(\dfrac{-3}{4}\right)\)

\(=\left(\dfrac{-3}{2}\right)^2-\left[-2\dfrac{1}{3}-\dfrac{13}{12}:2\dfrac{3}{5}\right].\left(\dfrac{-3}{4}\right)\)

\(=\left(\dfrac{-3}{2}\right)^2-\left[\dfrac{-7}{3}-\dfrac{13}{12}:\dfrac{13}{5}\right].\left(\dfrac{-3}{4}\right)\)

\(=\left(\dfrac{-3}{2}\right)^2-\left[\dfrac{-7}{3}-\dfrac{5}{12}\right].\left(\dfrac{-3}{4}\right)\)

\(=\left(\dfrac{-3}{2}\right)^2-\dfrac{-11}{4}.\left(\dfrac{-3}{4}\right)\)

\(=\dfrac{9}{4}-\dfrac{-11}{4}.\left(\dfrac{-3}{4}\right)\)

\(=\dfrac{9}{4}-\dfrac{33}{16}\)

\(=\dfrac{3}{16}\)

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Hải Đăng
12 tháng 8 2017 lúc 10:48

\(d)\dfrac{21}{33}:\dfrac{11}{5}-\dfrac{13}{33}:\dfrac{11}{5}+\dfrac{25}{33}:\dfrac{11}{5}+\dfrac{6}{11}\)

\(=\dfrac{5}{11}.\left(\dfrac{21}{33}-\dfrac{13}{33}+\dfrac{25}{33}\right)+\dfrac{6}{11}\)

\(=\dfrac{5}{11}.1+\dfrac{6}{11}\)

\(=\dfrac{5}{11}+\dfrac{6}{11}\)

\(=\dfrac{11}{11}=1\)

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