a, -3/7 × 15/13 - 3/7 × 11/13 - 3/7 b, 5/6 + 1/6 : 4/3 c, (5/7 - 3/4 ) - 7/4 d, -6/5 - 2/3 e, 3/4 + 1/4 : (1- 1/4) f, -3/8 × 12/13

a, \(-\dfrac{3}{7}\times\dfrac{15}{13}-\dfrac{3}{7}\times\dfrac{11}{13}-\dfrac{3}{7}\)

\(=-\dfrac{3}{7}\times\left(\dfrac{15}{13}+\dfrac{11}{13}+1\right)\)

\(=-\dfrac{3}{7}\times\left(\dfrac{26}{13}+1\right)\)

\(=-\dfrac{3}{7}\times\left(2+1\right)\)

\(=-\dfrac{3}{7}\times3=-\dfrac{9}{7}\)

b, \(\dfrac{5}{6}+\dfrac{1}{6}:\dfrac{4}{3}\)

\(=\dfrac{5}{6}+\dfrac{1}{6}\times\dfrac{3}{4}\)

\(=\dfrac{20}{24}+\dfrac{3}{24}=\dfrac{23}{24}\)

c, \(\left(\dfrac{5}{7}-\dfrac{3}{4}\right)-\dfrac{7}{4}\)

\(=\dfrac{5}{7}-\dfrac{3}{4}-\dfrac{7}{4}\)

\(=\dfrac{5}{7}-\left(\dfrac{3}{4}+\dfrac{7}{4}\right)\)

\(=\dfrac{5}{7}-\dfrac{10}{4}\)\(=\dfrac{5}{7}-\dfrac{5}{2}\)

\(=\dfrac{10}{14}-\dfrac{35}{14}=\dfrac{-25}{14}\)

d, \(-\dfrac{6}{5}-\dfrac{2}{3}=-\dfrac{18}{15}-\dfrac{10}{15}=-\dfrac{28}{15}\)

e, \(\dfrac{3}{4}+\dfrac{1}{4}:\left(1-\dfrac{1}{4}\right)\)

\(=\dfrac{3}{4}+\dfrac{1}{4}:\dfrac{3}{4}\)

\(=\dfrac{3}{4}+\dfrac{1}{4}\times\dfrac{4}{3}\)

\(=\dfrac{3}{4}+\dfrac{1}{3}=\dfrac{9}{12}+\dfrac{4}{12}=\dfrac{13}{12}\)

f, \(-\dfrac{3}{8}\times\dfrac{12}{13}-\dfrac{3}{8}\times\dfrac{14}{13}\)

\(=-\dfrac{3}{8}\times\left(\dfrac{12}{13}+\dfrac{14}{13}\right)\)

\(=-\dfrac{3}{8}\times\dfrac{26}{13}\)\(=-\dfrac{3}{8}\times2=-\dfrac{6}{8}\)

Hãy giúp mọi người biết câu trả lời này thế nào?

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