Integration using an Abel transform

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Homework Help Overview

The discussion revolves around evaluating the integral \(\int \frac{e^{x}}{\sqrt{(1+e^{2x})(1-e^{4x})}}dx\) using an Abel transform. Participants are exploring substitutions and transformations to simplify the integral.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss changing the variable to \(u = e^x\) and transforming the integral accordingly. There are attempts to express the integral in terms of a new variable \(v\) and questions about the consistency of the substitutions made.

Discussion Status

The discussion is ongoing with participants questioning the validity of the substitutions and seeking clarification on the relationships between the variables \(u\) and \(v\). Some guidance has been offered regarding the transformations, but there is no explicit consensus on the correct approach yet.

Contextual Notes

Participants are navigating through potential inconsistencies in their substitutions and are attempting to clarify the relationships between the variables involved in the integral.

|mathematix|
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Homework Statement



Find the following integral:

Homework Equations



[tex]\int \frac{e^{x}}{\sqrt{(1+e^{2x})(1-e^{4x})}}dx[/tex]

The Attempt at a Solution



I changed the integral to: [tex]\int \frac{e^{x}}{(1+e^{2x})\sqrt{(1-e^{2x})}}dx[/tex]
The let u=e^x
The integral becomes: [tex]\int \frac{du}{(1+u^{2})\sqrt{(1-u^{2})}}[/tex]
I can do this the long way, such as on wolfram alpha but I want to use an Abel transform so let [tex]u=\sqrt{1-u^{2}}'[/tex]

[tex]\sqrt{1-u^{2}}'=-\frac{u}{\sqrt{1-u^2}} \therefore v^{2}=\frac{u^{2}}{1-u^{2}}[/tex]

[tex]du=\frac{dv}{\sqrt{1-u^{2}}}[/tex]

The integral becomes: [tex]\int \frac{dv}{1-u^{4}}[/tex]

I need to somehow get rid off the u and get the integral in terms of v so how can I do that?
 
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|mathematix| said:
The integral becomes: [tex]\int \frac{dv}{1-u^{4}}[/tex]

I need to somehow get rid off the u and get the integral in terms of v so how can I do that?
u2 = 1 - v2, no?
 
haruspex said:
u2 = 1 - v2, no?

How do you get that?
 
Maybe I misunderstood your substitutions. This doesn't seem to be consistent:
|mathematix| said:
[tex]u=\sqrt{1-u^{2}}'[/tex]

[tex]\sqrt{1-u^{2}}'=-\frac{u}{\sqrt{1-u^2}}[/tex]
Did you mean [tex]v=\sqrt{1-u^{2}}'[/tex]? If so, u2 = v2/(1+v2)
 
haruspex said:
Maybe I misunderstood your substitutions. This doesn't seem to be consistent:

Did you mean [tex]v=\sqrt{1-u^{2}}'[/tex]? If so, u2 = v2/(1+v2)

Thanks :)
 

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