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

Toán Lớp 6: Bài1:Tính nhanh nếu có thể a)12-(-7) b)-18+15 c)25.(-39)+25.(-239) d)-120+(-85)+20+(-15)

Toán Lớp 6: Bài1:Tính nhanh nếu có thể
a)12-(-7)
b)-18+15
c)25.(-39)+25.(-239)
d)-120+(-85)+20+(-15)

Comments ( 2 )

  1. a)12-(-7)
    =12+7
    =19
    b)-18+15
    =-(18-15)
    =-3
    c)25.(-39)+25.(-239)
    =25.[(-39)+(-239)]
    =25.(-278)
    =-6950
    d)-120+(-85)+20+(-15)
    =[(-120)+20)]+[(-85)+(-15)]
    =100-(-100)
    =100+100
    =200 
     

  2. Answer
    a, 12 – (-7)
    = 12 + 7
    = 19
    _________________
    b, -18 + 15
    = -3
    __________________
    c, 25 . (-39) + 25 . (-239)
    = 25 . (-39 – 239)
    = 25 . (-278)
    = -6950
    ___________________
    d, -120 + (-85) + 20 + (-15)
    = -120 – 85 + 20 – 15
    = (-120 + 20) – (85 + 15)
    = -100 – 100
    = -200

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

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