Solve Non-Linear ODE with a Substitution | Step-by-Step Guide

In summary, the conversation discusses finding a good substitution for a non-linear ODE with the equation xy''+y'+(y')^3 = 0, where ' = d/dx. The person asking for help believes that an exact analytical solution exists because it is a problem in a text, but the responder states that most non-linear differential equations cannot be solved exactly. They suggest reducing the order of the equation by letting z= y' and solving for z in the first order separable equation xz'+ z+ z3= 0, and then letting y'= z.
  • #1
SeReNiTy
170
0
Hi guys, just wondering if you can give a hand on a non-linear ODE, all you guys need to do if give me a good substituion to try...

xy''+y'+(y')^3 = 0

where ' = d/dx
 
Physics news on Phys.org
  • #2
Do you have any reason to believe there is a "good substitution"?

Almost all non-linear differential equations cannot be solved exactly.
 
  • #3
Because this is a problem in a text, so i believe when thye say find the exact analytical solution, they must mean one exists...
 
  • #4
Okay, that's a good reason! Also I just noticed that you have y' twice and no y. If you let z= y', you can reduce the order of the equation:
xy''+y'+(y')^3 = 0 becomes xz'+ z+ z3= 0, a first order, separable equation. Solve for z and let y'= z.
 

FAQ: Solve Non-Linear ODE with a Substitution | Step-by-Step Guide

What is a Non-Linear ODE?

A Non-Linear ODE (Ordinary Differential Equation) is a type of mathematical equation that involves a dependent variable, its derivatives, and one or more independent variables. Unlike Linear ODEs, the dependent variable is not directly proportional to its derivatives, making the equation more complex to solve.

How do you solve a Non-Linear ODE?

Solving a Non-Linear ODE involves using various methods such as substitution, separation of variables, and series solutions. Each method requires a different approach and may not always result in an exact solution. In such cases, numerical methods can be used to approximate the solution.

What are the applications of Non-Linear ODEs?

Non-Linear ODEs have various applications in physics, engineering, and other areas of science. They are used to model complex systems that cannot be described by simple linear equations. Some examples include population growth, chemical reactions, and fluid dynamics.

How do Non-Linear ODEs differ from Linear ODEs?

The main difference between Non-Linear and Linear ODEs is that in Non-Linear ODEs, the dependent variable is not directly proportional to its derivatives. This makes the equations more complex and often requires numerical methods for solution. In contrast, Linear ODEs have a direct relationship between the dependent variable and its derivatives, making them easier to solve.

Can Non-Linear ODEs be solved analytically?

In some cases, Non-Linear ODEs can be solved analytically using mathematical techniques such as substitution, separation of variables, and series solutions. However, there are many Non-Linear ODEs that do not have an exact analytical solution, and numerical methods must be used to approximate the solution.

Similar threads

Replies
4
Views
404
Replies
3
Views
2K
Replies
6
Views
1K
Replies
1
Views
2K
Replies
3
Views
3K
Back
Top