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#1 2015-01-11 01:56:10

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
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Infinite Series

I'm wondering what is the best way to sum this:

I've one way:

Last edited by Agnishom (2015-01-11 01:56:46)


'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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#2 2015-01-11 04:44:33

anonimnystefy
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From: Harlan's World
Registered: 2011-05-23
Posts: 16,049

Re: Infinite Series

Last edited by anonimnystefy (2015-01-11 04:45:25)


“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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#3 2015-01-11 04:50:33

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,974
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Re: Infinite Series

Why does d/dx come there?


'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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#4 2015-01-11 04:53:02

anonimnystefy
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From: Harlan's World
Registered: 2011-05-23
Posts: 16,049

Re: Infinite Series

Well, you differentiate term by term.


“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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#5 2015-01-11 04:53:56

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,974
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Re: Infinite Series

Great!


'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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#6 2015-01-11 05:18:46

anonimnystefy
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From: Harlan's World
Registered: 2011-05-23
Posts: 16,049

Re: Infinite Series

Both approaches need to be made more rigorous, I think. I should note that those equations are all valid only under the circumstance that |x|<1. You need to prove that the sum converges in order to use that.


“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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#7 2015-01-11 13:20:40

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,974
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Re: Infinite Series

Well, doesn't post 2 show that the sum converges?


'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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#8 2015-01-11 13:51:41

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,049

Re: Infinite Series

I'd say no, but I was referring to post #1.


“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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#9 2015-01-11 15:19:41

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,974
Website

Re: Infinite Series

Why'd you say no?


'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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#10 2015-01-11 22:06:31

Olinguito
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Registered: 2014-08-12
Posts: 649

Re: Infinite Series

[list=*]
[*]

[/*]
[/list]

The sum of the nth column is

[list=*]
[*]

[/*]
[/list]

Hence

[list=*]
[*]

[/*]
[/list]


Bassaricyon neblina

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