Làm hộ mik câu 16;17;18

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Làm hộ mik câu 16;17;18
lam-ho-mik-cau-16-17-18

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Sigridomena 5 years 2020-11-25T15:29:15+00:00 2 Answers 75 views 0

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  1. giahuy
    0
    2020-11-25T15:30:15+00:00
    Reply

    Đáp án:

     $16)\dfrac{-21}{85}\\
    17)
    0\\
    18)
    \dfrac{-108}{7}$

    Giải thích các bước giải:

     $16)\left ( 2\dfrac{2}{15}.\dfrac{9}{17}.\dfrac{3}{32} \right ):\left ( -\dfrac{3}{7} \right )\\
    =\dfrac{32}{15}.\dfrac{9}{17}.\dfrac{3}{32}.\dfrac{-7}{3}\\
    =\dfrac{32}{15}.\dfrac{9}{17}.\dfrac{-7}{32}\\
    =\dfrac{32.9.(-7)}{15.17.32}\\
    =\dfrac{3^2.(-7)}{3.5.17}\\
    =\dfrac{-21}{85}\\
    17)
    \left ( \dfrac{-3}{4}+\dfrac{2}{5} \right ):\dfrac{3}{7}+\left ( \dfrac{3}{5}+\dfrac{-1}{4} \right ):\dfrac{3}{7}\\
    =\left ( \dfrac{-3}{4}+\dfrac{2}{5} \right ).\dfrac{7}{3}+\left ( \dfrac{3}{5}+\dfrac{-1}{4} \right ).\dfrac{7}{3}\\
    =\dfrac{3}{7}.\left ( \dfrac{-3}{4}+\dfrac{2}{5}+\dfrac{3}{5}-\dfrac{1}{4} \right )\\
    =\dfrac{3}{7}.\left ( \dfrac{-4}{4}+\dfrac{5}{5} \right )\\
    =\dfrac{3}{7}.(-1+1)\\
    =0\\
    18)
    \dfrac{7}{8}:\left ( \dfrac{2}{9}-\dfrac{1}{18}\right ):\dfrac{7}{8} :\left ( \dfrac{1}{36}-\dfrac{5}{12} \right )\\
    =\dfrac{7}{8}:\left ( \dfrac{4}{18}-\dfrac{1}{18}\right ):\dfrac{7}{8} :\left ( \dfrac{1}{36}-\dfrac{15}{36} \right )\\
    =\dfrac{7}{8}:\dfrac{3}{18}:\dfrac{7}{8}:\dfrac{-14}{36}\\
    =\dfrac{7}{8}:\dfrac{1}{6}:\dfrac{7}{8}:\dfrac{-7}{18}\\
    =\dfrac{7}{8}.6.\dfrac{8}{7}.\dfrac{-18}{7}\\
    =\dfrac{7.6.8.(-18)}{8.7.7}\\
    =\dfrac{6.(-18)}{7}\\
    =\dfrac{-108}{7}$

  2. Sapo1
    0
    2020-11-25T15:31:02+00:00
    Reply

    Cách làm của mk có hơi dài 1 chút

     

    lam-ho-mik-cau-16-17-18

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