Second order differential equation

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SUMMARY

The general solution to the second order differential equation y'' - 2(y')^2 = 0 can be approached by substituting u = y'. This leads to the first-order equation u' - 2u^2 = 0, which simplifies to u' = 2u^2. The correct method involves expressing u' as du/dx, allowing the use of separation of variables to solve the equation effectively.

PREREQUISITES
  • Understanding of second order differential equations
  • Familiarity with the concept of substitution in differential equations
  • Knowledge of separation of variables technique
  • Basic calculus, specifically differentiation and integration
NEXT STEPS
  • Study the method of separation of variables in depth
  • Learn about first-order differential equations and their solutions
  • Explore the implications of substituting variables in differential equations
  • Investigate the general solutions of nonlinear differential equations
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Students studying differential equations, mathematicians focusing on calculus, and educators teaching advanced mathematics concepts.

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Homework Statement



What is the general solution to y'' - 2(y')^2 = 0 ?


Homework Equations





The Attempt at a Solution



Let u = y '

u ' - 2u^2 = 0
u ' = 2u^2
u = (2 / 3)u^3 + C

This cannot be solved using separation of variables, what is done?
 
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your first step is correct when you chose u=y' , then you got the equation:
u'-2u^2=0 ,then : u'=2u^2

I believe that the last step you did is not correct, as far as i remember you should write u' = du/dx (or du/dt) according to what function is y originally, then from there you can use separation of variables .. :)
 

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