Friday, April 27, 2018

sequences and series - Convergence of sumin=1nftyfracsin2(n)n



Does the series n=1sin2(n)n converge?



I've tried to apply some tests, and I don't know how to bound the general term, so I must have missed something. Thanks in advance.


Answer



Hint:


Each interval of the form [kπ+π6,(k+1)ππ6) contains an integer nk. We then have, for each k, that sin2(nk)nk(1/2)2(k+1)π. Now use a comparison test to show your series diverges.



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