Help with solving a first order linear and first order non-linear

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Discussion Overview

The discussion revolves around solving a first order linear differential equation and a first order non-linear differential equation. Participants share their attempts at solving these equations and seek advice on the methods used.

Discussion Character

  • Technical explanation, Debate/contested, Mathematical reasoning

Main Points Raised

  • One participant presents an image of a first order linear differential equation and notes that their attempt leads to an integral that cannot be solved.
  • Another participant identifies a specific equation, (1-y)dx+xydy=0, and suggests finding the integrating factor using the formula 1/M(M_y-N_x).
  • A subsequent reply indicates that the integrating factor is not working and expresses a belief that it can only be used when the two partial derivatives differ by a constant, which they claim is not the case here.
  • A participant mentions that the solution y(x) cannot be expressed in terms of a finite number of elementary functions, implying that a closed form requires a special function.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the effectiveness of the integrating factor method, and there are competing views regarding the solvability of the equations presented.

Contextual Notes

There are limitations regarding the assumptions made about the applicability of the integrating factor method and the nature of the solutions, which remain unresolved.

Xyius
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Here is an image of the first order linear differential equation and my attempt to solve it. It ends in an integral that can not be solved.

http://img831.imageshack.us/img831/9937/math1.gif

And here is an image of the first order non-linear differential equation and my attempt to solve it. This one leads to a non-separable differential equation after a substitution.

http://img215.imageshack.us/img215/4893/math2.gif

Any advise?
 
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You have:

[tex](1-y)dx+xydy=0[/tex]

You can find the [itex]1/M(M_y-N_x)[/itex] integrating factor for that.
 
jackmell said:
You have:

[tex](1-y)dx+xydy=0[/tex]

You can find the [itex]1/M(M_y-N_x)[/itex] integrating factor for that.

The integrating factor isn't working. I was under the impression you can only use the integrating factor only when the two partials differ by a constant only, which they do not. :\
 
Separable ODE :
 

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y(x) cannot be expressed in terms of a finite number of elementary functions. The closed form requires a special function :
 

Attachments

  • ExpIntegral.JPG
    ExpIntegral.JPG
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