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

Toán Lớp 7: a) -1/21+ -1/28 b) -8/18 – 15/27 c) -5/12 +0,75 d) 3,5 – (-2/7)

Toán Lớp 7: a) -1/21+ -1/28
b) -8/18 – 15/27
c) -5/12 +0,75
d) 3,5 – (-2/7)

Comments ( 2 )

  1. a)
    -1/21+ -1/28
    = -4/84 + -3/84
    = -7/84
    = -1/12
    b)
    -8/18 – 15/27
    = -24/54 – 30/54
    = -24/54 + -30/54
    = -54/54
    = -1
    c)
    -5/12 + 0,75
    = -5/12 + 75/100
    = -5/12 + 3/4
    = -5/12 + 9/12
    = 4/12
    = 1/3
    d) 
    3,5 – (-2/7)
    = 35/10 – (-2/7)
    = 7/2 – (-2/7)
    = 49/14 – (-4/14)
    = 49/14 + 4/14
    = 53/14
    #Huy

  2. a) $\frac{-1}{21}+\frac{-1}{28}$
    $=\frac{-55}{756}$
    b) $\frac{-8}{18}-\frac{15}{27}$
    $=\frac{-4}{9}-\frac{5}{7}$
    $=\frac{-73}{63}$
    c) $\frac{-5}{12}+0,75$
    $=\frac{-5}{12}+\frac{3}{4}$
    $=\frac{1}{3}$
    d) $\frac{3}{5}-\frac{-2}{7}$
    $=\frac{3}{5}+\frac{2}{7}$
    $=\frac{31}{35}$

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

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