Nonlinear differential equation

Click For Summary
SUMMARY

The discussion focuses on solving the nonlinear differential equation y'' + 4(y')^2 + 8 = 0. The user initially attempts to substitute u = y' and derives the equation u(du/dy) + 4u^2 + 8 = 0. However, they later recognize that directly using u' + 4u^2 + 8 = 0 is more effective. The conversation emphasizes the importance of identifying Bernoulli equations for easier solutions in first-order differential equations.

PREREQUISITES
  • Understanding of differential equations, specifically second-order and first-order types.
  • Familiarity with substitution methods in differential equations.
  • Knowledge of Bernoulli equations and their characteristics.
  • Basic calculus concepts, including derivatives and integrals.
NEXT STEPS
  • Study the methods for solving Bernoulli equations in detail.
  • Explore the implications of nonlinear differential equations in various applications.
  • Learn about substitution techniques for simplifying differential equations.
  • Investigate the relationship between first-order and second-order differential equations.
USEFUL FOR

Students and educators in mathematics, particularly those focusing on differential equations, as well as researchers and professionals dealing with nonlinear systems in engineering and physics.

CINA
Messages
60
Reaction score
0

Homework Statement



[tex]y''+4\left(y'\right)^{2}+8=0[/tex]

Homework Equations



[tex]u=y'?[/tex]

The Attempt at a Solution



I don't really know where to start, do I use u=y' substituted? So, y''=u*(du/dy)?

That leads to [tex]u\frac{du}{dy}+4u^{2}+8=0[/tex]

I don't think this is correct, since it leads to [tex]y(x)=-\frac{u^{2}}{16}-\frac{ln (u)}{4}[/tex]
 
Physics news on Phys.org
Why not just let u=y' and get:

[tex]u'+4u^2+8=0[/tex]

and try and remember that whenever you have a first-order equation with a [itex]u^n[/itex] term, try to see if it's a Bernoulli equation which is easily solved.
 

Similar threads

  • · Replies 12 ·
Replies
12
Views
3K
Replies
19
Views
3K
  • · Replies 12 ·
Replies
12
Views
2K
Replies
5
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
Replies
3
Views
2K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
6
Views
3K
Replies
5
Views
2K