\(\dfrac{-5}{7}.\dfrac{2}{11}+\dfrac{-5}{7}.\dfrac{9}{14}+\dfrac{6}{7}\)
\(=\dfrac{-5}{11}.\dfrac{2}{7}+\dfrac{-5}{11}.\dfrac{9}{7}+\dfrac{6}{7}\)
\(=\dfrac{-5}{11}\left(\dfrac{2}{7}+\dfrac{9}{7}\right)+\dfrac{6}{7}\)
\(=\dfrac{-5}{11}.\dfrac{11}{7}+\dfrac{6}{7}\)
\(=\dfrac{-5}{7}+\dfrac{6}{7}\)
\(=\dfrac{1}{7}\)
\(-\dfrac{5}{7}.\dfrac{2}{11}+\dfrac{-5}{7}.\dfrac{9}{14}+\dfrac{6}{7}\)
\(=-\dfrac{5}{7}\left(\dfrac{2}{11}+\dfrac{9}{14}\right)+\dfrac{6}{7}=-\dfrac{5}{7}.\dfrac{127}{154}+\dfrac{6}{7}\)
\(=-\dfrac{635}{1078}+\dfrac{6}{7}=\dfrac{289}{1078}\)
Vậy...............
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\(\dfrac{-5}{7}\times\dfrac{2}{11}+\dfrac{-5}{7}\times\dfrac{9}{14}+\dfrac{6}{7}\)
\(=\dfrac{-5}{7}\times\left(\dfrac{2}{11}+\dfrac{9}{14}\right)+\dfrac{6}{7}\)
\(=\dfrac{-5}{7}\times\dfrac{127}{154}+\dfrac{6}{7}\)
\(=\dfrac{-635}{1078}+\dfrac{6}{7}\)
\(=\dfrac{289}{1078}\)
