Thursday, 28 July 2016

calculus - Does this series converge or diverge? $sum_{n=1}^inftylnleft(1+frac1{n^2}right)$



I have a series here, and I'm supposed to determine whether it converges or diverges. I've tried the different tests, but I can't quite get the answer.




$$\sum_{n=1}^\infty\ln\left(1+\frac1{n^2}\right)$$




Answer



Hint: Recall that $\ln(1+x)\sim x$ for $x\to 0$, and use the fact that $\sum_{n=1}^\infty\frac1{n^2}$ is convergent.


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