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MathsMediumMCQ2013 · 09 Apr Online

Q65.The sum of the series: 1 + 1+21 + 1+2+31 + … …. upto 10 terms, is: (1) 18 (2) 22 11 13 (3) 20 (4) 16 11 9 2 15

What This Question Tests

This question requires identifying the general term of the series, which involves the sum of natural numbers in the denominator, and then summing the resulting terms using a telescoping technique.

Concepts Tested

Sum of first n natural numbersGeneral term of a seriesTelescoping sum

Formulas Used

Σk = k(k+1)/2

Σ(1/(k(k+1))) = Σ(1/k - 1/(k+1))

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