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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 7: thực hiện phép tính a 3/8 . 19 1/3 – 3/8 . 33 1/3 b 5/7 . ( -3/11) + 5/7 . ( -8/11) + 2 5/7

Toán Lớp 7: thực hiện phép tính
a 3/8 . 19 1/3 – 3/8 . 33 1/3
b 5/7 . ( -3/11) + 5/7 . ( -8/11) + 2 5/7

Comments ( 2 )

  1. a)
    3/8 . 19 1/3 – 3/8 . 33 1/3
    = 3/8 . (19 1/3 – 33 1/3)
    = 3/8 . (19 + 1/3 – 33 – 1/3)
    = 3/8 . [(19-33) + (1/3-1/3)]
    =  3/8 . (-14)
    = -21/4
    b)
    5/7 . (-3/11) + 5/7 . (-8/11) + 2 5/7
    = 5/7 . (-3/11 + (-8)/11) + 2 5/7
    = 5/7 . (-1) + 5/7 + 2
    = -5/7 + 5/7 + 2
    = 0+2
    = 2

  2. Giải đáp:
    a) $\dfrac{-21}4$
    b) $2$
    Lời giải và giải thích chi tiết:
    $a)\,\dfrac38\cdot19\dfrac13-\dfrac38\cdot33\dfrac13\\=\dfrac38\cdot\left(19\dfrac13-33\dfrac13\right)\\=\dfrac38\cdot\bigg(19-33\bigg)\\=\dfrac38\cdot(-14)\\=\dfrac{-21}{4}\\b)\,\dfrac57\cdot\dfrac{-3}{11}+\dfrac57\cdot\dfrac{-8}{11}+2\dfrac57\\=\dfrac57\cdot\left(\dfrac{-3}{11}+\dfrac{-8}{11}\right)+2\dfrac57\\=\dfrac{5}7\cdot(-1)+2\dfrac57\\=\dfrac{-5}7+2\dfrac57\\=2$

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222-9+11+12:2*14+14 = ? ( )

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