A) 3/5+-1/3 B) -2/13+-11/26 C) -2+-5/8 D)13/30-1/5 E) 2/21+-1/28

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A) 3/5+-1/3 B) -2/13+-11/26 C) -2+-5/8 D)13/30-1/5 E) 2/21+-1/28

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Faith 3 tuần 2021-09-07T08:23:46+00:00 2 Answers 1 views 0

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    0
    2021-09-07T08:25:34+00:00

    Đáp án:

    \(a,\ \dfrac{4}{15}\\ b,\ \dfrac{-15}{26}\\ c,\ \dfrac{-21}{8}\\ d,\ \dfrac{7}{30}\\ e,\ \dfrac{5}{84}\)

    Giải thích các bước giải:

    \(a,\ \dfrac{3}{5}+\left (\dfrac{-1}{3} \right )=\dfrac{3.3}{5.3}+\dfrac{(-1).5}{3.5}=\dfrac{9}{15}+\dfrac{-5}{15}=\dfrac{4}{15}\\ b,\ \left (\dfrac{-2}{13} \right )+\left (\dfrac{-11}{26} \right )=\left (\dfrac{-2.2}{13.2} \right )+\left (\dfrac{-11}{26} \right )=\left (\dfrac{-4}{26} \right )+\left (\dfrac{-11}{26} \right )=\dfrac{-15}{26}\\ c,\ (-2)+\left (\dfrac{-5}{8} \right )=\left (\dfrac{-2.8}{8} \right )+\left (\dfrac{-5}{8} \right )=\left (\dfrac{-16}{8} \right )+\left (\dfrac{-5}{8} \right )=\dfrac{-21}{8}\\ d,\ \dfrac{13}{30}-\dfrac{1}{5}=\dfrac{13}{30}-\left (\dfrac{1.6}{5.6} \right )=\dfrac{13}{30}-\dfrac{6}{30}=\dfrac{7}{30}\\ e,\ \dfrac{2}{21}+\left (\dfrac{-1}{28} \right )=\left (\dfrac{2.4}{21.4} \right )+\left (\dfrac{-1.3}{28.3} \right )=\dfrac{8}{84}+\left (\dfrac{-3}{84} \right )=\dfrac{5}{84}\)

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    0
    2021-09-07T08:25:41+00:00

    Đáp án:

     

    Giải thích các bước giải:

     a) 3/5 + (-1/3)

    =9/15 + (-5/15)

    =4/15

    b)(-2/13) + (-11/26)

    =(-4/26) + (-11/26)

    =-15/26

    c)(-2) + (-5/8)

    =(-16/8) + (-5/8)

    =-21/8

    d)13/30 – 1/5

    =13/30 – 6/30

    =7/30

    e)2/21 + (-1/28)

    =8/64 + (-3/64)

    =-21/64

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