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Nov
25
comment Determining limit points and proving there are no more of them
@TonyK: Oh I see the mistake - using the absolute value of $b_n$ always yields positive results which is no reason why $b_n$ should be bounded.
Nov
25
revised Determining limit points and proving there are no more of them
added 89 characters in body
Nov
25
comment Determining limit points and proving there are no more of them
@TonyK: Could you give an example why this isn't true?
Nov
25
comment Determining limit points and proving there are no more of them
@DonAntonio: Yeah thats one issue here I would like to solve, too. Any help is appreciated.
Nov
25
asked Determining limit points and proving there are no more of them
Nov
19
accepted Examination of convergence of a few series
Nov
19
comment Examination of convergence of a few series
After a break I will work through your comments and rethink my ideas. Thanks for your effort.
Nov
19
comment Examination of convergence of a few series
Concerning 5 I do not understand what you mean by saying the $k$-th term is positive - shouldn't that include something like "for every even k"? Furthermore does that mean the series does not converge absolutely?
Nov
19
comment Examination of convergence of a few series
@ThomasAndrews: $$\frac{1}{k+3+2/k}\geq \frac{1}{2}$$.
Nov
19
comment Examination of convergence of a few series
@ThomasAndrews: Does $1/2$ suffice?
Nov
19
comment Examination of convergence of a few series
@ThomasAndrews: Would it be correct to remove the sums and to just look at the sequences rather than the series?
Nov
19
asked Examination of convergence of a few series
Nov
18
comment Cauchy product and the exponential function
Thank you so much - you do help me every time!
Nov
18
accepted Cauchy product and the exponential function
Nov
18
comment Cauchy product and the exponential function
WolframAlpha showed me that I should get $1/2\sin(2x)$ as a result, however the $4^n$ makes it difficult to derive the fact that I have to get $(2x)^{2n+1}$ and the $1/2$ in front of everything. This is what I want to know right now.
Nov
18
comment Cauchy product and the exponential function
@BrianM.Scott: I have made another approach, may I ask you to have a look at it?
Nov
18
revised Cauchy product and the exponential function
added second attempt of this problem
Nov
17
comment Cauchy product and the exponential function
@BrianM.Scott: Now I do understand this - do you have a hint (rather than the solution ;) ) for the second series for me?
Nov
17
comment Cauchy product and the exponential function
@BrianM.Scott: But you have $\sum_{n\ge 0}\frac{2^n}{n!}=(e-1)^2$ and that confuses me.
Nov
17
comment Cauchy product and the exponential function
@BrianM.Scott: I have a question. Your first result is $(e-1)^2$ but I think it should be $e^2$, shouldn't it?