Tuesday, July 23, 2019

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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