Solving ODE with Bernoulli's Method: y''+(y')2 = y

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Homework Help Overview

The problem involves solving a second-order ordinary differential equation (ODE) of the form y'' + (y')² = y, with initial conditions y(0) = 1 and y'(0) = 1/√2. The discussion centers around the application of Bernoulli's method for this type of equation.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the substitution of p = y' and the implications of this substitution on the equation. There are questions about the correct formulation of the derivatives and potential issues arising from the notation used. Some participants express uncertainty about the chain rule and its application in this context.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the substitution and its effects on the equation. One participant indicates they have resolved their confusion after extensive work, suggesting that some progress has been made, but no consensus or final solution has been reached.

Contextual Notes

There is mention of potential complications arising from the use of multiple variables (p, z, y, x) and the need for careful application of the chain rule, indicating that clarity in notation and understanding is crucial for solving the problem.

manenbu
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Homework Statement



y''+(y')2 = y, y(0)=1, y'(0)=1/√2

Homework Equations



Bernoulli's method.

The Attempt at a Solution



Using the substitution p=y' I get this:
p'p + p2 = y, so I can use z=p2 to solve this.
However, I'm getting something wrong.
I think it could be because I'm having too much letters - p, z, y, x so I might be missing some chain rules.
 
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Not worked through this, but using the substitution p = y', surely you would get:

p'+p^2 = y and NOT p'p +p^2?
 
but I'm using p(y), not p(x)
so y'' = dp/dy dy/dx = dp/dy p = p' p
 
oh well, I got it. Took me 2 pages of text. If you're interested I can post the solution here. :)
 

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