- #1
lkh1986
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Homework Statement
By using the Euler's constant (0.577...), express the limit of the sum 1/n + 1/(n+1) + ... + 1/2n explicitly as n goes to infinity.
Homework Equations
The limit as n goes to infinity for [1/1 + 1/2 + ... + 1/n - In (n)] is the Euler constant, 0.577...
It has been deduced and shown previously that the limit of the sum 1/n + 1/(n+1) + ... + 1/2n is between 0.5 and 1. And the value lies somewhere around 0.6-0.75.
The Attempt at a Solution
I think the word "explicitly" in the question means that we need to express the answer in terms of the Euler's constant.
limit as n goes to infinity for [1/1 + 1/2 + ... + 1/n - In (n)] = 0.577...
Let a (subscript k) = 1/k + 1/(k+1) + ... + 1/2k and k<n
limit as k goes to infinity for [1/1 + 1/2 + ...1/(k-1) + 1/k + 1/(k+1)+...+1/2k +1/(2k+1) ... 1/n - In (n)] = 0.577...
limit as k goes to infinity for [1/1 + 1/2 + ...1/(k-1) + a(subscript k) + 1/(2k+1) ... 1/n - In (n)] = 0.577...
limit as k goes to infinity for [a(subscript k)] = 0.577... - limit as k goes to infinity [1/1 + 1/2 + ...1/(k-1)] - limit as k goes to infinity [(1/(2k+1) + ... + 1/n] + limit as k goes to infinity [In(n)]
Then I don't know how to continue. Perhaps I need to define other variables? It seems that k and n are a bit confusing...
Thanks.