I'm trying to determine whether ∞∑n=1(n√2−1)
In this question the answerer very smartly (I have no idea how he/ she thought to do that) used the fact that (1+1n)n≤e≤3 to bound n√3−1 by 1n but that only worked because 3≥e. So even though that question looks very similar I don't think I can apply that idea here.
Edit: This is in the section before power/ Taylor series so I don't think I'm allowed to use that.
Answer
Hint:
n√2−1=elog2n−1=log2n+O(n−2)
as n→∞.
ADDENDUM
To address your specific problem, consider instead
(1+log2n)n
which you should be able to show is less than 2. I that case, then you can show that n√2−1>(log2)/n and draw your conclusion about the sum.
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