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

Toán Lớp 6: Tính hợp lí ( phá ngoặc, nếu có) : (-2005) + [ (-21) + 75 + 2005 (55 + 45 + 15) – (15 – 55 + 45) (-87) + (-12) – (-487) + 512

Toán Lớp 6: Tính hợp lí ( phá ngoặc, nếu có) :
(-2005) + [ (-21) + 75 + 2005
(55 + 45 + 15) – (15 – 55 + 45)
(-87) + (-12) – (-487) + 512

Comments ( 2 )

  1. a)
    (-2005) + [ (-21) + 75 + 2005]
    =(-2005)+(-21)+75+2005
    =[(-2005)+2005]+(75-21)
    =0+54
    =54
    b)
    (55+45+15)-(15-55+45)
    =55+45+15-15+55-45
    =(55+55)+(45-45)+(15-15)
    =110+0+0
    =110
    c)
    -87 + ( -12 ) – ( -487 ) + 512
    = [ ( -12 ) + 512 ] + [ ( -87 ) – ( -487 ) ]
    = 500 + 400
    =900
    _______________________________________________
    (mik ghi a,b,c cho dễ phân biệt từng câu)
    $@Masonn$

  2. Lời giải chi tiết:
    a) -2005+[(-21)+75+2005]
    =-2005+(-21+75+2005)
    =-2005-21+75+2005
    =(-2005+20005)+(75-21)
    =0+54
    b) (55+45+15)-(15-55+45)
    =55+45+15-15+55-45
    =(45-45)+(55+55)+(15-15)
    =0+110+0
    =110
    c) (-87)+(-12)-(-487)+512
    =-87-12+487+512
    =(-87+487)+(512-12)
    =400+500
    =900

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