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#51 2011-07-02 00:40:48

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,522

Re: Integration by Substitution

got that one.dunno what to do next.


“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

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#52 2011-07-02 00:52:35

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 86,481

Re: Integration by Substitution

Hi;

gAr has a substitution that you will look at too.


In mathematics, you don't understand things. You just get used to them.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.

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#53 2011-07-02 01:04:43

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,522

Re: Integration by Substitution

hi

what substitution?


“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

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#54 2011-07-02 01:06:56

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 86,481

Re: Integration by Substitution

My way has led to a integration by parts which is tediuos but amounts to  plugging in to a formula.

If gAr has something else it may save you a whole lot of work. So let us wait for him.


In mathematics, you don't understand things. You just get used to them.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.

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#55 2011-07-02 01:10:10

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,522

Re: Integration by Substitution

ok,sure.just a question,is it possible to send private messages on this forum?


“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

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#56 2011-07-02 01:11:26

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 86,481

Re: Integration by Substitution

Yes, you must be a real member. That is awarded by MIF. Only he can do it.


In mathematics, you don't understand things. You just get used to them.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.

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#57 2011-07-02 01:12:53

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,522

Re: Integration by Substitution

yeah,how often does he come to the forum,because i don't see him active very much?


“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

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#58 2011-07-02 01:15:37

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 86,481

Re: Integration by Substitution

I see him every day.


In mathematics, you don't understand things. You just get used to them.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.

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#59 2011-07-02 01:17:24

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,522

Re: Integration by Substitution

when?


“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

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#60 2011-07-02 01:19:01

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,522

Re: Integration by Substitution

me and MIF must be opposite time zones.


“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

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#61 2011-07-02 01:20:03

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 86,481

Re: Integration by Substitution

I think so. Also he is usually busy working on the site.


In mathematics, you don't understand things. You just get used to them.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.

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#62 2011-07-02 01:21:36

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,522

Re: Integration by Substitution

let's stop this or otherwise there's a possibility that this topic turns into a chat topic.


“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

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#63 2011-07-02 01:24:37

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 86,481

Re: Integration by Substitution

Brought to the front by moderator.

Hi

anonimnystefy wrote:

can anyone help me get:


In mathematics, you don't understand things. You just get used to them.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.

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#64 2011-07-02 01:48:41

gAr
Member
Registered: 2011-01-09
Posts: 3,479

Re: Integration by Substitution

Hi,

First lets derive a general formula for


First method is a more common one, integration by parts.
We'll need to use IBP twice, where we end up with the original integral on the RHS, and rearrange it.

Another method struck me:


Constant is not so cool to look at, I agree!


"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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#65 2011-07-02 01:55:53

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,522

Re: Integration by Substitution

hi gAr

thanks.never thought of 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

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#66 2011-07-02 02:12:57

gAr
Member
Registered: 2011-01-09
Posts: 3,479

Re: Integration by Substitution

Hi anonimnystefy,

You're welcome!

The constant is not "not cool" as I thought.
I forgot about substituting x back in the answer!

So what remains is:

Last edited by gAr (2011-07-02 02:13:25)


"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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#67 2011-07-17 04:57:17

gAr
Member
Registered: 2011-01-09
Posts: 3,479

Re: Integration by Substitution

Hi,


A huge list of integrals, for fun and practice!
http://mpec.sc.mahidol.ac.th/radok/phys … /sec41.htm
http://mpec.sc.mahidol.ac.th/radok/phys … /sec42.htm
http://mpec.sc.mahidol.ac.th/radok/phys … /sec51.htm

Skimming over it, I can say the problems have a quality!

That site is wonderful!
Don't miss the library: http://mpec.sc.mahidol.ac.th/library/oldbooks

Last edited by gAr (2011-07-17 05:21:07)


"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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#68 2011-08-01 22:55:16

gAr
Member
Registered: 2011-01-09
Posts: 3,479

Re: Integration by Substitution

Hi,

From AMM sad
11275

Find


"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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#69 2011-08-08 09:48:49

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,522

Re: Integration by Substitution

here's one:


“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

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#70 2011-08-08 18:33:00

gAr
Member
Registered: 2011-01-09
Posts: 3,479

Re: Integration by Substitution

Hi anonimnystefy,


"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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#71 2011-08-08 23:36:07

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,522

Re: Integration by Substitution

hi gAr

thanks for looking for the problem.


“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

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#72 2011-08-09 00:13:23

gAr
Member
Registered: 2011-01-09
Posts: 3,479

Re: Integration by Substitution

Hi anonimnystefy,

I'm not finished with it yet!
I posted it in haste because I had to go out for a while.
Now I'll take a longer look.


"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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#73 2011-08-09 00:23:15

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,522

Re: Integration by Substitution

hi gAr

it's ok,take your time.


“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

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#74 2011-08-09 06:59:09

gAr
Member
Registered: 2011-01-09
Posts: 3,479

Re: Integration by Substitution

Hi anonimnystefy,


"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

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#75 2011-08-09 09:10:00

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,522

Re: Integration by Substitution

ok i will be waiting.

i don't have the solution.


“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

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