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

Toán Lớp 9: `A= 7/6+13/12+21/20+31/30+43/42`

Tháng Hai 11, 2023 Toán học 2 Comments 0 views

Toán Lớp 9: A= 7/6+13/12+21/20+31/30+43/42

Comments ( 2 )

  1. baoquyen
    baoquyen
    11 Tháng Hai, 2023 at 11:38 chiều
    Reply
    Giải đáp:
     A = 75/14
    Lời giải và giải thích chi tiết:
     7/6 + 13/12 + 21/20 + 31/30 + 43/42
    = (6+1)/6 + (12 + 1)/12 + (20+1)/20 + (30 +1)/30 + (42+ 1)/42
    = 6/6 + 1/6 + 12/12 +1/12 + 20/20 + 1/20 + 30/30 + 1/30 + 42/42 + 1/42
    = 1 + 1/6 + 1 + 1/12 + 1 + 1/20 + 1 + 1/30 + 1 + 1/42
    = (1 + 1 + 1 + 1 + 1) + (1/6 + 1/12 +1/20 + 1/30  +1/42)
    = 1 . 5 + (1/(2.3) + 1/(3.4) + 1/(4.5) + 1/(5.6) + 1/(6.7))
    = 5 + (1/2 – 1/3 + 1/3 – 1/4 + 1/4 – 1/5 + 1/5 – 1/6 + 1/6 – 1/7)
    = 5 + (1/2 – 1/7)
    = 70/14 + 7/14 – 2/14
    = 75/14
    Vậy A = 75/14

  2. maianh67
    maianh67
    11 Tháng Hai, 2023 at 11:37 chiều
    Reply
    A=7/6+13/12+21/20+31/30+43/42
    A=6/6+1/6+12/12+1/12+20/20+1/20+30/30+1/30+42/42+1/42
    A=1+1/6+1+1/12+1+1/20+1+1/30+1+1/42
    A=(1+1+1+1+1)+(1/6+1/12+1/20+1/30 +1/42)
    A=1×5+(1/(2×3)+1/(3×4)+1/(4×5)+1/(5×6)+1/(6×7))
    A=5+(1/2−1/3+1/3−1/4+1/4−1/5+1/5−1/6+1/6−1/7)
    A=75/14
    Em làm như này được ko mod???

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

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