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

Toán Lớp 6: Bài 1:Tính nhanh : a) 2006 x 125 + 1000 ______________________ 126 x 2005 – 888 b) 2020 x 99 + 1921 _____________________ 100

Toán Lớp 6: Bài 1:Tính nhanh :
a) 2006 x 125 + 1000
______________________
126 x 2005 – 888

b) 2020 x 99 + 1921
_____________________
100 x 2019 – 19

Comments ( 2 )

  1. a,
    (2006 × 125 + 1000)/(126 × 2005 – 888)
    = (2006 × 125 + 1000)/((125 + 1) × 2005 – 888)
    = (2006 × 125 + 1000)/(125 × 2005 + 2005 – 888)
    = (2006 × 125 + 1000)/(125 × 2005 + 1117)
    = ((2005 + 1) × 125 + 1000)/(125 × 2005 + 1117)
    = (2005 × 125 + 125 + 1000)/(125 × 2005 + 1117)
    = (2005 × 125 + 1125)/(125 × 2005 + 1117)
    = 1125/1117
    b,
    (2020 × 99 + 1921)/(100 × 2019 – 19)
    = (2020 × 99 + 1921)/((99 + 1) × 2019 – 19)
    = (2020 × 99 + 1921)/(99 × 2019 + 2019 – 19)
    = (2020 × 99 + 1921)/(99 × 2019 + 2000)
    = ((2019 + 1) × 99 + 1921)/(99 × 2019 + 2000)
    = (2019 × 99 + 99 + 1921)/(99 × 2019 + 2000)
    = (2019 × 99 + 2020)/(99 × 2019 + 2000)
    = 2020/2000
    = 101/100

  2. a) 2006 x 125 + 1000 / 126 x 2005 – 888
    = (2005 + 1) x 125 + 1000/(125 + 1) x 2005 – 888
    = 2005 x 125 +125 +1000/125 x 2005 + 2005 – 888
    = 2005 x 125 + 1125/125 x 2005 + 1117
    = 1125/1117
    b) 2020 x 99 + 1921/100 x 2019 – 19
    = (2019 + 1) x 99 + 1921/(99 + 1) x 2019 – 19
    = 2019 x 99 + 99 +1921/99 x 2019 + 2019 – 19
    = 2019 x 99 + 2920/99 x 2019 + 2000
    = 101/100

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