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

Toán Lớp 6: 13 – 14 + 15 – 16 + 17 – 18 + … + 2019 – 2020 giúp với

Toán Lớp 6: 13 – 14 + 15 – 16 + 17 – 18 + … + 2019 – 2020
giúp với

Comments ( 2 )

  1. Lời giải và giải thích chi tiết:
    13 – 14 + 15 – 16 + 17 – 18 +………..+ 2019 – 2020
    = (13 + 15 + 17 +……+2019) – ( 14+16+18+……..+2020)
    = {[(2019-13):2+1] . (2019+13):2} – {[(2020-14):2+1] . (2020+14) : 2}
    = { 1004 . 1016 } – { 1004 . 1017 }
    = 1004 . ( 1016 – 1017 )
    = 1004 . (-1)
    = -1004

  2. Answer
    13 – 14 + 15 – 16 + 17 – 18 + … + 2019 – 2020
    = (13 – 14) + (15 – 16) + (17 – 18) + … + (2019 – 2020)
    = \underbrace{(-1) + (-1) + (-1) + … + (-1)}_{\text{Có 1004 số -1}}
    = (-1) . 1004
    = -1004

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