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#1 Help Me ! » Unbounded sequence that doesnt diverge to -∞ or ∞ » 2007-02-12 08:59:58
- woodoo
- Replies: 3
I have a question that says find an unbounded sequence that doesn't diverge to -∞ or ∞. I can't figure one out, I don't think it exists. Anyone know of one?
#2 Help Me ! » Help with an approximation of Dirichlet's Test » 2007-02-12 05:51:33
- woodoo
- Replies: 0
As used in another thread I have this problem
I am asked to find the value of n to approximate the series to the millionth place, then find that approximation. I am confused by this wording. Does anyone understand this and know how I should go about doing this? Thanks
#3 Help Me ! » Help with a series » 2007-02-12 05:40:41
- woodoo
- Replies: 2
I have this problem that I can't figure out.
a_n is a sequence of positive #s. For each n in the natural #s, b_n = (a1+a2+...+an)/n. And I have to use this to show
∞
∑ b_n
n=1
diverges to positive infinity. Any1 have any ideas?
#4 Re: Help Me ! » I don't understand Dirichlet's Test » 2007-02-12 05:32:57
So if Zhylliolom right? Because you guys are confusing me
#5 Re: Help Me ! » I don't understand Dirichlet's Test » 2007-02-11 20:15:28
Oh I understand now, I thought that {bn} was going to have to equal (sin n)/n, I didn't realize you were supposed to break down (sin n)/n into {an} = 1/n and {bn} = sin n to represent
Thank you Zhylliolom
#6 Help Me ! » I don't understand Dirichlet's Test » 2007-02-11 19:47:42
- woodoo
- Replies: 14
I can't grasp the concept of Dirichlet's Test,
I've looked online, but I don't understand it. Can someone give me a simple example to explain it.
Thanks
edit: I think what is confusing me is this:
Am I supposed to prove that is true or do I just assume it is?
#7 Help Me ! » Converges or Diverges, did I do this right? » 2007-02-11 17:37:45
- woodoo
- Replies: 1
I have the problem which I must find convergent or divergent:
infinity _____
∑ 1/(√n^3-2)
n= 2
I used the Comparison Test with a p-series to get that it's convergent. Is this correct?
_____ ____
1/(√n^3-2) < 1/(√n^3) = 1/n^(3/2) so it converges
#8 Re: Help Me ! » Help me make this converge » 2007-02-11 14:54:17
wow that was a lot easier than I thought, thank you
#9 Help Me ! » Help me make this converge » 2007-02-11 13:46:06
- woodoo
- Replies: 2
The problem I have wants me to prove the following statement false:
"If a_n and b_n are both divergent sequences then (a_n + b_n) diverges also."
I can't come up with a two divergent sequences that with converge if I add them together. Anyone have any ideas? Thanks
#10 Re: Help Me ! » Help with Dirichlet's test » 2007-02-11 11:15:59
Are you sure an isn't (sin(n))/n ?
#11 Help Me ! » Help with Dirichlet's test » 2007-02-10 21:55:10
- woodoo
- Replies: 4
I need to use Dirichlet's test to show
infinity
∑ (sin(n))/n converges
n=1
Would 1/n work for bn? And how shall I go about solving this.
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