(tricky) first order ODE


by mmh37
Tags: order, tricky
mmh37
mmh37 is offline
#1
Apr15-06, 09:04 AM
P: 61
Does anyone see how one can tackle the following ODE?

[tex] [2y*exp^{y/x} + x}] \frac {dy} {dx} -2x - 2y = 0 [/tex]

that is my attempt:

rearrange to get

[tex] dy/dx = \frac {2x + 2y} {2y*exp^{y/x}-x} [/tex]

I do not see how to go on from here. Surely, the ODE is not seperabale and I don't find a way to get the integrating factor here.

thanks for any hints!

[edit:] for a more clearly written version of the ODE see attached file
Attached Thumbnails
Zwischenablage01.jpg  
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Astronuc
Astronuc is offline
#2
Apr15-06, 02:09 PM
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P: 21,637
First thought would be to try a change of variable, u = y/x, so

du/dx = (1/x) dy/dx - y/x2 = (1/x) dy/dx - u/x


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