Tuesday, April 23, 2019

sequences and series - converges or diverges? sumin=1nftysin2(fracpin)



n=1sin2(πn)



First, I tried Divergence test, but the limit is 0, so that's inconclusive. I don't think I can do integral test, since it's not a clean integration.




Did I do this right ? If it's wrong, can you steer me in the right direction? I tried subbing in 1cos(x) for the sin(x). This would get:



n=1sin2(πn)
=n=11cos2(πn)
=n=11n=1sin2(πn)
But that first sigma is divergent to infinity, so does the original series also diverge to infinity?



The tests I know are: Geometric, p-series, Divergence (nth term) test, Integral test, Direct Comparison test, Alternating Series Test, Absolute convergence, and Ratio test.


Answer




Using sin(x)x for all x0 so by comparison with the convergent series 1n2 we conclude the convergence of the given series.


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