Non-linear first order ODE: Solving with Exact Form

In summary, the conversation is about trying to solve the given ODE, ydx+(\frac {e^x}{y}-1)dy=0, by attempting to transfer it into exact form and using an integrating factor. However, the attempts were unsuccessful, and the person is seeking help to find the correct solution.
  • #1
estro
241
0
I'm trying to solve the following ODE: [tex] ydx+(\frac {e^x}{y}-1)dy=0[/tex]

I tried to transfer this ODE into exact form but no luck.

Will appreciate any help.
 
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  • #2
estro said:
I'm trying to solve the following ODE: [tex] ydx+(\frac {e^x}{y}-1)dy=0[/tex]

I tried to transfer this ODE into exact form but no luck.

Will appreciate any help.

Leave the equation as it is and look for an integrating factor that is just a function of x.
 
  • #3
I tried it before:
[tex]X=y, Y=e^x/y-1[/tex]
[tex]u'(x)+(\frac {X_y-Y_x}{Y})u(x)=0[/tex]
Thus u=e^x

But [tex]d/dy(e^xX) \neq d/dx(e^xY)[/tex]

What I'm missing?
 
  • #4
estro said:
I tried it before:
[tex]X=y, Y=e^x/y-1[/tex]
[tex]u'(x)+(\frac {X_y-Y_x}{Y})u(x)=0[/tex]

Are you sure about the sign on that numerator?
 
  • #5
Bellow is formula that I found in my book:
[tex]u'(x)+(\frac {X_y-Y_x}{Y})u(x)=0[/tex]=
[tex]u'(x)-u(x)=0[/tex] => u=e^x

Can't see where is the problem.
 
  • #6
LCKurtz said:
Are you sure about the sign on that numerator?

estro said:
Bellow is formula that I found in my book:
[tex]u'(x)+(\frac {X_y-Y_x}{Y})u(x)=0[/tex]=
[tex]u'(x)-u(x)=0[/tex] => u=e^x

Can't see where is the problem.

I told you what was wrong. The numerator should be Yx-Xy.
 

Related to Non-linear first order ODE: Solving with Exact Form

1. What is a non-linear first order ODE?

A non-linear first order ODE (ordinary differential equation) is an equation that involves the first derivative of a function with respect to the independent variable, and the function itself is raised to a power or multiplied by another function. This makes it a non-linear equation, as the dependent variable is not directly proportional to the independent variable.

2. How is a non-linear first order ODE different from a linear first order ODE?

In a linear first order ODE, the dependent variable is directly proportional to the independent variable, and the equation can be solved using separation of variables. However, in a non-linear first order ODE, the dependent variable is not directly proportional to the independent variable, and different methods such as substitution or numerical approximation may be needed to solve it.

3. What are some real-world applications of non-linear first order ODEs?

Non-linear first order ODEs are commonly used in physics, engineering, and other fields to model complex systems such as population growth, chemical reactions, and electrical circuits. They can also be used to study the behavior of biological systems, economics, and climate change.

4. How do you solve a non-linear first order ODE?

There are several methods for solving non-linear first order ODEs, such as substitution, numerical approximation, and power series solutions. The method used will depend on the specific equation and the techniques known to the mathematician. In some cases, it may not be possible to find an exact solution and numerical methods may be used instead.

5. What are the challenges in solving non-linear first order ODEs?

One of the main challenges in solving non-linear first order ODEs is that there is no general method that can be applied to all equations. Each equation may require a different approach, and some equations may not have an exact solution at all. Additionally, non-linear equations can exhibit chaotic behavior, making it difficult to predict the behavior of the system over time.

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