Math Is Fun Forum
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#26 2013-05-18 15:58:16
Re: Sum this.
Yes, that I've seen
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#27 2013-05-18 16:05:34
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Sum this.
Now the notation does the rest. We can write
Where
is the nth Fibonacci number.
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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#28 2013-05-18 16:18:42
Re: Sum this.
Hmmm...
The next challenge is to find something whose taylor series is 5x + 5^2*x^2 + 5^3*x^3....
Which we could do with the formula of GP but to bad, I've forgotten that
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#29 2013-05-18 16:21:05
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Sum this.
One second we are getting there.
We can further write.
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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#30 2013-05-18 16:25:08
Re: Sum this.
Yes, thats just the same thing with some more notation
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#31 2013-05-18 16:28:55
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Sum this.
Okay, if we substitute 1 / 5 for x we get, (1/5), ( 1/5)^2, (1/5)^3...
or written as
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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#32 2013-05-18 16:32:41
Re: Sum this.
yes great! 
Awesome!
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#33 2013-05-18 16:37:01
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Sum this.
I have not changed anything on the LHS, so lets do that now.
Make the substitution:
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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#34 2013-05-18 16:38:19
Re: Sum this.
We are done with that, I guess...
Now the big question is how did you find a function whose taylor series contains the fibonacci?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#35 2013-05-18 16:41:04
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Sum this.
You do not have to, x / (1 - x - x^2) is the generating function. Each problem has a different gf usually. Some are so useful they have hundreds of uses for that gf like the Catalan numbers,
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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#36 2013-05-18 16:44:23
Re: Sum this.
x / (1 - x - x^2) is the generating function.
How did you come to know?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#37 2013-05-18 16:46:37
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Sum this.
Because basically they are derived from the recurrence that states the problem. f(n) = f(n-1) + f(n-2). That is one way.
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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#38 2013-05-18 17:55:31
Re: Sum this.
Would you show their derivation?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#39 2013-05-18 18:20:44
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Sum this.
Hi;
Off hand I do not remember how. I will post when I find it.
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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#40 2013-05-18 19:06:33
Re: Sum this.
http://en.wikipedia.org/wiki/Fibonacci_ … wer_series
Please see this and explain it to me 
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#41 2013-05-18 19:12:43
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Sum this.
Hi Agnishom;
I do not like his proof. For one thing, F0 makes little sense to me.
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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#42 2013-05-18 19:26:46
Re: Sum this.
But, I thought you were talking about this one
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#43 2013-05-18 23:08:41
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Sum this.
Hi;
Straight out of Wilf's book.
We start with:
multiply the LHS by x^n and sum over n+1 to get,.
On the RHS we get:
Solving for F(x) we get:
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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#44 2013-05-19 00:47:14
Re: Sum this.
How did you get that by multiplying the LHS with x^n? 
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#45 2013-05-19 00:49:41
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Sum this.
Beats me! Herbert is about 200 times smarter than me.
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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#46 2013-05-19 01:07:54
Re: Sum this.
Does it mean you understand it neither?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#47 2013-05-19 01:13:37
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Sum this.
I do not understand his derivation. I rarely understand someone else's proof or program. I always have to do it myself to have any chance.
I had a method that was so good it worked on a small programmable calculator. I do not remember it 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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#48 2013-05-19 01:15:40
Re: Sum this.
What is a programmable calculator?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#49 2013-05-19 01:20:11
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Sum this.
Today they call them graphic calculators.
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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#50 2013-05-21 14:34:14
Re: Sum this.
How is the taylor series of sin found out?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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