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

Toán Lớp 6: Bài 1:Tính hợp lí A)-13.(57-34)+57.(13-45) B)125.(-24)+24.225 C)63.(-25)+25.(-23) D)-2019+12.(-76)-76.(-34) E)(37-17).(-5)+23.(-13-17)

Toán Lớp 6: Bài 1:Tính hợp lí
A)-13.(57-34)+57.(13-45)
B)125.(-24)+24.225
C)63.(-25)+25.(-23)
D)-2019+12.(-76)-76.(-34)
E)(37-17).(-5)+23.(-13-17)
G)(-37).(55-23)-55.(23-37)

Comments ( 2 )

  1. a, -13.(57-34)+57.(13-45)
    = -13 . 57 – ( -13 ) . 34 + 57 . 13 – 57 . 45
    = ( -13 . 57 + 57 . 13 ) – ( -13 ) . 34 – 57 . 45
    = 0 + 442 – 2565
    = 2123
    b, 125.(-24)+24.225
    = -125 . 24 + 24 . 225
    = 24 ( -125 + 225 )
    = 24 . 100
    = 2400
    c, 63.(-25)+25.(-23)
    = -63 . 25 + 25 . ( -23)
    = 25 ( -63 – 23 )
    = 25 . ( -86 )
    = -2150
    d, -2019+12.(-76)-76.(-34)
    = -2019 + ( -76 ).(12 – 34 )
    = -2019 + ( – 76 ) . (-22)
    = -2019- 1672
    =-347
    e, (37-17).(-5)+23.(-13-17)
    = 20 . ( -5 ) + 23 . ( -30 )
    = -100 – 690
    = -790
    g, (-37).(55-23)-55.(23-37)
    = -37 . 55 – ( -37 ) . 23 – 55 . 23 – 55 ( – 37 )
    = [ -37 . 55 – 55 ( – 37 )] + 37 . 23 – 55 . 23
    = 0 + 23 ( – 37 – 55 )
    = 23 . ( -18 )
    = -414

  2.     Ron
    Bài 1:Tính hợp lí
    A) -13 . (57 – 34) + 57 . (13 – 45)
     = -13 . 57 – (-13) . 34 + 57 . 13 – 57 . 45
     = (-13 . 57 – 57 . 13) – (-13) . 34 – 57 . 45
     = 0 – (-442) – 2565
     = -2123
    —-
    B) 125 . (-24) + 24 . 225
     = -125 . 24 + 24 . 225
     = 24 . (-125 + 225)
     = 24 . 100
     = 2400
    —- 
    C) 63 . (-25) + 25 . (-23)
     = -63 . 25 + 25 . (-23)
     = 25 . [-63 + (-23)]
     = 25 . (-86)
     = -2150
    —-
    D) -2019 + 12 . (-76) – 76 . (-34)
     = -2019 + (-12) . 76 – 76 . (-34) 
     = -2019 + 76 . [(-12) – (-34)]
     = -2019 + 76 . 22
     = -2019 + 1672
     = -347
    —-
    E) (37 – 17) . (-5) + 23 . (-13 – 17)
     = 20 . (-5) + 23 . (-30)
     = -100 + (-690)
     = -790
    —-
    G) (-37) . (55 – 23) – 55 . (23 – 37)
     = (-37) . 55 – (-37) . 23 – 55 . 23 – 55 . 37
     = [(-37) . 55 – 55 . 37] + 23 . (37 – 55)
     = 0 + 23 . (-18)
     = -414

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

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