Help Solving a Diff. Equation: Ideas Needed

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SUMMARY

The discussion focuses on solving the differential equation (x e^{\frac{y}{x}} + 2x^2 y)dy - y e^{\frac{y}{x}}dx = 0. Participants suggest using the substitution v = y/x, which transforms the equation into a more manageable form. The substitution leads to y' = v + v'x and allows for further simplification. Ultimately, the correct approach involves recognizing the need for substitutions to achieve an exact equation.

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manenbu
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Need help with solving this DE.

Homework Statement



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

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?
 
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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.
 
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