Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

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

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,809

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

Offline

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

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 81,414

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.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

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

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,809

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

Offline

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

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 81,414

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.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

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

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,809

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

Offline

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

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 81,414

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.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

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

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,809

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

Offline

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

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 81,414

Re: Integration by Substitution

I see him every day.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

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

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,809

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

Offline

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

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,809

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

Offline

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

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 81,414

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.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

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

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,809

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

Offline

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

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 81,414

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.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

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

gAr
Member
Registered: 2011-01-09
Posts: 3,462

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."

Offline

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

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,809

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

Offline

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

gAr
Member
Registered: 2011-01-09
Posts: 3,462

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."

Offline

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

gAr
Member
Registered: 2011-01-09
Posts: 3,462

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."

Offline

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

gAr
Member
Registered: 2011-01-09
Posts: 3,462

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."

Offline

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

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,809

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

Offline

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

gAr
Member
Registered: 2011-01-09
Posts: 3,462

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."

Offline

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

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,809

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

Offline

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

gAr
Member
Registered: 2011-01-09
Posts: 3,462

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."

Offline

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

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,809

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

Offline

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

gAr
Member
Registered: 2011-01-09
Posts: 3,462

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."

Offline

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

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,809

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

Offline

Board footer

Powered by FluxBB