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H24

Thực hiện phép tính: \(\dfrac{-3}{8}.\dfrac{2}{7}+\dfrac{-3}{8}.\dfrac{5}{7}+\left|\dfrac{-7}{8}\right|\)

NV
19 tháng 5 2022 lúc 13:15

\(\dfrac{-3}{8}.\dfrac{2}{7}+\dfrac{-3}{8}.\dfrac{5}{7}+\left|\dfrac{-7}{8}\right|\)

\(=\dfrac{-3}{8}.\left(\dfrac{2}{7}+\dfrac{5}{7}\right)+\dfrac{7}{8}\)

\(=\dfrac{-3}{8}+\dfrac{7}{8}\)

\(=\dfrac{1}{2}\)

 

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H24
19 tháng 5 2022 lúc 13:15

\(=\dfrac{-3}{8}\cdot\left(\dfrac{2}{7}+\dfrac{5}{7}\right)+\dfrac{7}{8}\\ =-\dfrac{3}{8}\cdot1+\dfrac{7}{8}\\ =-\dfrac{3}{8}+\dfrac{7}{8}\\ =\dfrac{4}{8}=\dfrac{1}{2}\)

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NT
19 tháng 5 2022 lúc 13:16
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H24
19 tháng 5 2022 lúc 13:39

\(\dfrac{-3}{8}.\dfrac{2}{7}+\dfrac{-3}{8}.\dfrac{5}{7}+\left|\dfrac{-7}{8}\right|\)

\(=\dfrac{-3}{8}.\left(\dfrac{2}{7}+\dfrac{5}{7}\right)+\dfrac{7}{8}\)

\(=\dfrac{-3}{8}.1+\dfrac{7}{8}\)

\(=\dfrac{-3}{8}+\dfrac{7}{8}\)

\(=\dfrac{4}{8}=\dfrac{1}{2}\)

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