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

Toán Lớp 5: $\frac{2}{3×5}$ + $\frac{2}{5×7}$ + $\frac{2}{7×9}$ + $\frac{2}{11×13}$ + $\frac{2}{13×15}$ =

Toán Lớp 5: $\frac{2}{3×5}$ + $\frac{2}{5×7}$ + $\frac{2}{7×9}$ + $\frac{2}{11×13}$ + $\frac{2}{13×15}$ =

Comments ( 2 )

  1. 2/(3xx5) + 2/(5xx7) + 2/(7xx9) + 2/(11xx13) + 2/(13xx15)
    = 1/3 – 1/5 + 1/5 – 1/7 + 1/7 – 1/9 + 1/11 – 1/3 + 1/13 – 1/15
    = 1/3 – 1/9 + 1/11 – 1/15
    = 2/9 + (1/11 – 1/15)
    = 2/9 + 4/164
    = 122/495
     

  2. Giải đáp:
    122/495
    Lời giải và giải thích chi tiết:
    2/(3 × 5) + 2/(7 × 9) + 2/(11 × 13) + 2/(13 × 15)
    = 1/3 – 1/5 + 1/5 – 1/7 + 1/7 – 1/9 + 1/11 – 1/3 + 1/13 – 1/15
    = 1/3 – 1/9 + 1/11 – 1/15
    = 2/9 + (1/11 + 1/15)
    = 122/495

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