Find general solution, 1st order ODE

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Homework Help Overview

The discussion revolves around finding the general solution to a first-order ordinary differential equation (ODE) presented in the form of a Bernoulli equation. The equation involves terms with both \(y\) and its derivative, along with an exponential function of \(x\).

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to manipulate the equation into a Bernoulli form and expresses confusion regarding an integral that appears non-elementary. Another participant suggests that the equation might be separable, while a third participant reinforces the idea that it resembles a Bernoulli type ODE.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the equation. Some guidance has been offered regarding the nature of the ODE, but there is no explicit consensus on the best approach to take.

Contextual Notes

Participants note a potential error in the original manipulation of the equation, which may have led to confusion regarding the integral. There is also mention of constraints related to the types of integrals that have been covered in their studies.

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Homework Statement



Find a general solution.

Homework Equations



2x\frac{dy}{dx}+y^{3}e^{-2x}=2xy

The Attempt at a Solution



Looks like a Bernoulli equation to me, after some algebra:

\frac{dy}{dx}+\frac{y^{3}}{2xe^{2x}}=y

\frac{dy}{dx}+\frac{y}{2xe^{2x}}=y^{-1}

so with n=-1
v=y^{2}, y=v^{1/2}, \frac{dy}{dx}=\frac{1}{2}v^{-1/2}\frac{dv}{dx}

\frac{1}{2}v^{-1/2}}\frac{dv}{dx}+\frac{v^{1/2}}{2xe^{2x}}=v^{-1/2}

\frac{1}{2}\frac{dv}{dx}+\frac{v}{2xe^{2x}}=1

\frac{dv}{dx}+\frac{v}{xe^{2x}}=2

Now an integrating factor:

\mu=exp[\int{x^{-1}e^{-2x}dx}]

And that's where I get stuck. This doesn't look like any elementary integral I've learned how to solve, and wolfram|alpha gives me something called the "exponential integral" which we haven't been taught. So I've done something wrong, but I don't see it.

Thanks for any insights.
 
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Ok, I think I found my error: I forgot to divide the dy/dx by y^2 when I obtained y^-1 as the RHS. No wonder I wound up with a nonelementary integral. However, I'm still stuck.

I don't recognize this equation, and manipulating it around trying to "force it" to be in first-order linear, homogeneous, or bernoulli hasn't helped. So I'm stuck.

This is where I am, and don't recognize it:

\frac{dy}{dx}+\frac{y^{3}}{2xe^{2x}}=y
 
Isn't that separable? Split up the differentials?
 
This is just another Bernoulli type ODE isn't it?
 

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