How Can This Non-Separable First Order ODE Be Solved?

So the ODE becomesx du/dx + 2u = 2uexp(u)This is a Bernoulli equation. In summary, the conversation discusses the attempt to tackle the given ODE and the suggestion to use a change of variable to transform it into a Bernoulli equation.
  • #1
mmh37
59
0
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
 

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  • #2
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
 

FAQ: How Can This Non-Separable First Order ODE Be Solved?

What is a first order ordinary differential equation (ODE)?

A first order ODE is an equation that involves a single independent variable and its first derivative (with respect to that variable). It is an equation that relates a function to its slope at a given point.

How do I solve a first order ODE?

The most common method for solving first order ODEs is by separation of variables. This involves isolating the dependent and independent variables on opposite sides of the equation and then integrating both sides. Other methods include substitution, exact equations, and using integrating factors.

What is the difference between an exact and an inexact first order ODE?

An exact first order ODE is one in which the differential equation can be written in the form M(x,y)dx + N(x,y)dy = 0, where M and N are functions of x and y. In this case, the solution can be found by integrating both sides. An inexact first order ODE does not have this form and requires an integrating factor to be solved.

Can first order ODEs have multiple solutions?

Yes, first order ODEs can have multiple solutions. This is because the general solution of a first order ODE contains one arbitrary constant, which can take on different values to result in different solutions. In some cases, an initial condition or boundary condition can be used to determine the specific solution.

What are some real-life applications of first order ODEs?

First order ODEs have many applications in various fields of science and engineering. Some examples include population growth models in biology, radioactive decay in physics, and electrical circuits in engineering. They are also used in economics, chemistry, and many other areas to model and predict various phenomena.

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