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

Toán Lớp 5: 1/ 1 x 2 + 1/ 2 x 3 + 1/ 3 x 4 + 1/ 4 x5 +-. 1/ 100 x 101

Toán Lớp 5: 1/ 1 x 2 + 1/ 2 x 3 + 1/ 3 x 4 + 1/ 4 x5 +….. 1/ 100 x 101

Comments ( 2 )

  1. 1/ 1 x 2 + 1/ 2 x 3 + 1/ 3 x 4 + 1/ 4 x5 +….. 1/ 100 x 101
    = 1 – 1/2 + 1/2 – 1/3 + 1/3 –  1/4 + …….. + 1/100 – 1/101
    = 1 – 1/ 101
    = 100/101 

  2. 1/(1×2)+1/(2×3)+1/(3×4)+…+1/(100×101)
    =1/1-1/2+1/2-1/3+1/3-1/4+…+1/100-1/101
    =1/1+(-1/2+1/2)+(-1/3+1/3)+…+(-1/100+1/100)-1/101
    =1/1-1/101=101/101-1/101
    =100/101
    $\text{@ThanhTruc2008}$

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