Sunday, 13 December 2015

analysis - Showing that a sequence converges (in metric space)



In (,.), how would I show that xn=(n+1n,n+22n,n+33n,...) converges and how would I find the limit?



I tried using the fact that the uniform norm .=sup|Xn| and the definition of convergence is that given ϵ>0, there exists NN such that d(xn,x)<ϵ for all n>N, but I cant seem to show it converges. How would I show it converges and find the limit?


Answer



We denote x(n) the sequence of sequences. Then x(n)k=n+kkn=1k+1n, and we can write x(n)=a(n)+b(n) where a(n)k=1k for all n and b(n)k=1n. We have ||b(n)||=1n which converges to 0 and a(n) doesn't depend on n. Denoting this sequence a, we can see that lim.


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