Question

Đã trả lời bởi chuyên gia

Answer 1

a,

$(\frac{1}{2} - \frac{13}{14}) \div \frac{5}{7} - (\frac{- 2}{21} + \frac{1}{7}) \div \frac{5}{7} = (\frac{1}{2} - \frac{13}{14} + \frac{2}{21} - \frac{1}{7}) \div \frac{5}{7} = (\frac{21}{42} - \frac{39}{42} + \frac{4}{42} - \frac{6}{42}) \div \frac{5}{7} = \frac{- 20}{42} \times \frac{7}{5} = \frac{- 2 \times 2 \times 5 \times 7}{2 \times 3 \times 7 \times 5} = \frac{- 2}{3} b, \frac{- 3}{7} . \frac{5}{11} + \frac{- 5}{14} . \frac{5}{11} = \frac{- 5}{11} . (\frac{3}{7} + \frac{5}{14}) = \frac{- 5}{11} . \frac{11}{14} = \frac{- 5}{14} c, \frac{- 1}{24} - [\frac{1}{4} - (\frac{1}{2} - \frac{7}{8})] = \frac{- 1}{24} - \frac{1}{4} + \frac{1}{2} - \frac{7}{8} = \frac{- 1}{24} - \frac{6}{24} + \frac{12}{24} - \frac{21}{24} = \frac{- 16}{24} = \frac{- 2}{3}$

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Answer 2

a,

$(\frac{1}{2} - \frac{13}{14}) \div \frac{5}{7} - (\frac{- 2}{21} + \frac{1}{7}) \div \frac{5}{7} = (\frac{1}{2} - \frac{13}{14} + \frac{2}{21} - \frac{1}{7}) \div \frac{5}{7} = (\frac{21}{42} - \frac{39}{42} + \frac{4}{42} - \frac{6}{42}) \div \frac{5}{7} = \frac{- 20}{42} \times \frac{7}{5} = \frac{- 2 \times 2 \times 5 \times 7}{2 \times 3 \times 7 \times 5} = \frac{- 2}{3} b, \frac{- 3}{7} . \frac{5}{11} + \frac{- 5}{14} . \frac{5}{11} = \frac{- 5}{11} . (\frac{3}{7} + \frac{5}{14}) = \frac{- 5}{11} . \frac{11}{14} = \frac{- 5}{14} c, \frac{- 1}{24} - [\frac{1}{4} - (\frac{1}{2} - \frac{7}{8})] = \frac{- 1}{24} - \frac{1}{4} + \frac{1}{2} - \frac{7}{8} = \frac{- 1}{24} - \frac{6}{24} + \frac{12}{24} - \frac{21}{24} = \frac{- 16}{24} = \frac{- 2}{3}$

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