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Câu 1:

\(-12+\left(16-11\right).4=-12+5.4=-12+20=8\) 

Câu 2:

\(2\dfrac{3}{7}+1\dfrac{4}{7}=\dfrac{17}{7}+\dfrac{11}{7}=\dfrac{17+11}{7}=\dfrac{28}{7}=4\) 

Câu 3:

\(\dfrac{-2}{3}.\dfrac{4}{5}+\dfrac{1}{5}:\dfrac{9}{11}=\dfrac{-8}{15}+\dfrac{11}{45}=\dfrac{-13}{45}\)

21 tháng 5 2021

Câu 1:

\(-12+\left(16-11\right).4=-12+5.4=-12+20=8\)

Câu 2:

\(2\dfrac{3}{7}+1\dfrac{4}{7}=\dfrac{17}{7}+\dfrac{11}{7}=\dfrac{28}{7}=4\)

Câu 3: 

\(\dfrac{-2}{3}.\dfrac{4}{5}+\dfrac{1}{5}:\dfrac{9}{11}=\dfrac{-8}{15}+\dfrac{1}{5}.\dfrac{11}{9}=\dfrac{-8}{15}+\dfrac{11}{45}=\dfrac{-13}{45}\)

31 tháng 10 2021

A

Câu 1: 

\(\dfrac{2}{5}-\dfrac{1}{4}+\dfrac{3}{10}=\dfrac{8}{20}-\dfrac{5}{20}+\dfrac{6}{20}=\dfrac{8-5+6}{20}=\dfrac{9}{20}\) 

Câu 2:

\(\dfrac{-2}{5}:\left(1-\dfrac{1}{10}\right)=\dfrac{-2}{5}:\dfrac{9}{10}=\dfrac{-2}{5}.\dfrac{10}{9}=\dfrac{-2.10}{5.9}=\dfrac{-20}{45}=\dfrac{-4}{9}\) 

Câu 3:

\(\dfrac{7}{8}.\dfrac{4}{9}+\dfrac{1}{14}:\dfrac{5}{14}=\dfrac{7}{18}+\dfrac{1}{5}=\dfrac{53}{90}\) 

Câu 4:

\(\dfrac{2}{7}.\dfrac{3}{11}+\dfrac{2}{7}.\dfrac{8}{11}\) 

\(=\dfrac{2}{7}.\left(\dfrac{3}{11}+\dfrac{8}{11}\right)\) 

\(=\dfrac{2}{7}.1\) 

\(=\dfrac{2}{7}\)

21 tháng 5 2021

Câu 1

\(\dfrac{2}{5}\)-\(\dfrac{1}{4}\)+\(\dfrac{3}{10}\)\(\dfrac{8}{20}\)-\(\dfrac{5}{20}\)+\(\dfrac{6}{20}\)=\(\dfrac{3}{20}\)+\(\dfrac{6}{20}\)=\(\dfrac{9}{20}\)

Câu 2

-\(\dfrac{2}{5}\):(1-\(\dfrac{1}{10}\))= -\(\dfrac{2}{5}\):\(\dfrac{9}{10}\)=-\(\dfrac{2}{5}\).\(\dfrac{10}{9}\)=-\(\dfrac{4}{9}\)

Câu 3

\(\dfrac{7}{8}.\dfrac{4}{9}+\dfrac{1}{14}:\dfrac{5}{14}\)\(\dfrac{7}{8}.\dfrac{4}{9}+\dfrac{1}{14}.\dfrac{14}{5}\)=\(\dfrac{7.4}{4.2.9}+\dfrac{1.14}{14.5}\)=\(\dfrac{7}{18}+\dfrac{1}{5}\)=\(\dfrac{35}{90}+\dfrac{18}{90}\)=\(\dfrac{53}{90}\)

Câu 4

\(\dfrac{2}{7}.\dfrac{3}{11}+\dfrac{2}{7}.\dfrac{8}{11}\)=\(\dfrac{2}{7}.\left(\dfrac{3}{11}+\dfrac{8}{11}\right)\)=\(\dfrac{2}{7}.1\)=\(\dfrac{2}{7}\)

Câu 11: B

Câu 12: B

Câu 13: A

Câu 14: C

Câu 15: D

 

7 tháng 8 2021

Câu 13 :

\(\left(-\frac{1}{4}+\frac{5}{8}\right)+-\frac{3}{5}\)

\(=\frac{3}{8}-\frac{-3}{5}\)

\(=\frac{39}{40}\)

Câu 14 :

\(M=\frac{5}{9}.\frac{7}{13}+\frac{5}{9}.\frac{9}{13}-\frac{5}{9}.\frac{3}{13}\)

\(=\frac{5}{9}.\left(\frac{7}{13}+\frac{9}{13}-\frac{3}{13}\right)\)

\(=\frac{5}{9}.1=\frac{5}{9}\)

Câu 15 :

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

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

\(E=0\)

Câu 16 :

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

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

\(=\frac{7}{8}:\frac{-7}{24}=-3\)

7 tháng 8 2021

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18 tháng 8 2018

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