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#1 2016-02-26 13:55:32
- ErnChung
- Guest
closed-form expression
can somebody teach me part b
#2 2016-02-26 13:57:15
- ernchung
- Member
- Registered: 2016-02-26
- Posts: 14
Re: closed-form expression
http://imgur.com/E85FOE9
this is the question
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#3 2016-02-26 15:37:55
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: closed-form expression
Hi;
a) I am getting 1 when n = 0 and 0 for all other n.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#4 2016-02-26 19:35:34
- ernchung
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- Registered: 2016-02-26
- Posts: 14
Re: closed-form expression
yeah i also get this ans in part a
but i dunno how to do part b after expanding nCi and iCm.
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#5 2016-02-26 20:21:33
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: closed-form expression
For b, I am getting 1 when m = n and 0 when m ≠ n.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#6 2016-02-26 21:50:19
- ernchung
- Member
- Registered: 2016-02-26
- Posts: 14
Re: closed-form expression
would you like to show me the steps for part b?
for part a, one of my friend told me dat
he used (a-b)^n as example, he expanded it and found summation from 0 to n, (-1)^i * nCi * a^(n-i) * b^i
when a = b = 1, it will look like the same as part a and will equal to 0 no matter n=0 or not
how do you think?
Last edited by ernchung (2016-02-26 21:51:38)
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#7 2016-02-27 16:19:53
- ernchung
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- Registered: 2016-02-26
- Posts: 14
Re: closed-form expression
I manage to finish this question ty
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#8 2016-02-27 16:31:30
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: closed-form expression
What did you do?
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#9 2016-02-27 18:36:51
- ernchung
- Member
- Registered: 2016-02-26
- Posts: 14
Re: closed-form expression
https://www.dropbox.com/s/52vx1pp7ogy8ypr/20160228_173437.jpg?dl=0
how do you think?
please tell me if it is not correct
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#10 2016-02-28 05:05:33
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: closed-form expression
Sorry, I am unable to get to that link. Can you post the image?
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#11 2016-02-28 16:39:03
- ernchung
- Member
- Registered: 2016-02-26
- Posts: 14
Re: closed-form expression
I have placed it between the
[img]Place link to pretty picture right here.[/img]tags for you.
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#12 2016-02-29 05:57:52
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: closed-form expression
I am sorry but I can not see that very well, you did get the right answer though.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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