Solving an ODE by the method of Integrating Factors

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SUMMARY

The discussion focuses on solving the ordinary differential equation (ODE) y' + y = x y²/32 using the method of integrating factors. The challenge arises because the term Q is a function of both x and y, complicating the application of the integrating factors method typically used for equations where Q is solely a function of x. Participants suggest manipulating the equation to express the right-hand side in terms of x only, leading to the expression (d/dx) e^x y = x e^(x/3) (e^x y)^(2/3). This manipulation is crucial for progressing towards a solution.

PREREQUISITES
  • Understanding of ordinary differential equations (ODEs)
  • Familiarity with the method of integrating factors
  • Knowledge of functions and their derivatives
  • Basic algebraic manipulation skills
NEXT STEPS
  • Study the method of integrating factors in depth, particularly for non-linear ODEs
  • Learn how to manipulate ODEs to isolate variables effectively
  • Explore the concept of exact equations and when they apply
  • Investigate alternative methods for solving ODEs, such as substitution techniques
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Students and professionals in mathematics, particularly those studying differential equations, as well as educators looking for examples of integrating factors applied to non-standard ODEs.

1missing
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1. y' + y = x y2/32. The problem states we need to solve this ODE by using the method of integrating factors. Every example I found on the internet involving this method was of the form:

y' + Py = Q

Where P and Q are functions of x only. In the problem I was given however, Q is a function of both x and y. If I try to proceed with the method I end up with:

(d/dx) ex y = x ex y2/3


Annnnd that's where I'm stuck. Am I missing something here or was this problem incorrectly assigned?
 
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So what do you have to do to make the right-hand side a function in ##x## only ?
 
Divide by y2/3 on both sides of the original equation, but then I've got a term in front of the y' and that doesn't seem to get me closer to a solution.
 
What is ##\frac{d(y^{1/3})}{dx}## equal to?
 
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Son of a...I probably would've stared at this thing for a couple of days before I noticed that. That should get me to a solution, let me give it a go.
 
1missing said:
I end up with:
(d/dx) ex y = x ex y2/3

Annnnd that's where I'm stuck. Am I missing something here or was this problem incorrectly assigned?
You could also proceed by noting that the righthand side is equal to ##x e^{x/3} (e^x y)^{2/3}##.
 

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