Help Solving a Diff. Equation: Ideas Needed

  • Thread starter Thread starter manenbu
  • Start date Start date
  • Tags Tags
    Ideas
Click For Summary

Homework Help Overview

The discussion revolves around solving a differential equation involving a non-exact form and potential substitutions. The equation presented is (x e^{\frac{y}{x}} + 2x^2 y)dy - y e^{\frac{y}{x}}dx = 0.

Discussion Character

  • Exploratory, Assumption checking, Mixed

Approaches and Questions Raised

  • Participants explore various substitutions, such as v = y/x and v = x/y, to potentially simplify the equation. There is uncertainty about the effectiveness of these substitutions and whether they will lead to an exact equation.

Discussion Status

Some participants have offered different substitution strategies, indicating a collaborative exploration of possible approaches. There is acknowledgment of the need for further verification of these methods, and one participant notes a successful adjustment in their approach after initial confusion.

Contextual Notes

Participants express uncertainty regarding the initial steps and the nature of the differential equation, highlighting the challenge of working with non-exact forms and the implications of substitutions.

manenbu
Messages
101
Reaction score
0
Need help with solving this DE.

Homework Statement



[tex](x e^{\frac{y}{x}} + 2x^2 y)dy - y e^{\frac{y}{x}}dx = 0[/tex]

Homework Equations



The Attempt at a Solution



Well, I don't even know where to start. It's not exact, and I can't make it exact with an integrating factor. All of this y/x in here makes me think that maybe I need to make a substitution here, but I can't just use it like that because it wouldn't work.
Any ideas?
 
Physics news on Phys.org
I would start with v = y/x. I can't guarantee that it would work, since I haven't worked the problem, but it might be what you need to get an exact equation.

The substitution v = y/x is equivalent to y = vx, so y' = v + v'x.
 
Try using the substitution v = x/y which is equivalent to vy = x

So dx/dy = v + y*dv/dy

Give it a try and see if it works.
 
Yes it was, but I also had to make a substitution for y, missed it the first time.
Got it right now.

Thanks.
 

Similar threads

  • · Replies 8 ·
Replies
8
Views
2K
Replies
7
Views
2K
Replies
3
Views
2K
Replies
4
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 4 ·
Replies
4
Views
1K
Replies
5
Views
2K
Replies
3
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 18 ·
Replies
18
Views
3K