Second order differential equation

In summary, the general solution to y'' - 2(y')^2 = 0 is u = (2 / 3)u^3 + C, which cannot be solved using separation of variables. Instead, one must write u' = du/dx (or du/dt) and use separation of variables from there.
  • #1
scarlets99
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0

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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  • #2
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 .. :)
 

FAQ: Second order differential equation

What is a second order differential equation?

A second order differential equation is a mathematical equation that involves the second derivative of an unknown function. It represents the relationship between a function and its second derivative.

What is the difference between a first and second order differential equation?

The main difference between a first and second order differential equation is the highest order derivative present in the equation. A first order differential equation has the first derivative of the unknown function, while a second order differential equation has the second derivative.

What is the general form of a second order differential equation?

The general form of a second order differential equation is y'' = f(x,y,y'), where y is the unknown function, x is the independent variable, and y' and y'' represent the first and second derivatives of y, respectively.

What are some real-world applications of second order differential equations?

Second order differential equations are used to model various physical systems, such as the motion of a pendulum, the growth of a population, and the oscillations of a spring. They are also used in engineering to design and analyze systems, such as electrical circuits and control systems.

What methods can be used to solve a second order differential equation?

Some common methods for solving second order differential equations include separation of variables, variation of parameters, and the use of Laplace transforms. Numerical methods, such as Euler's method and Runge-Kutta methods, can also be used to approximate solutions to these equations.

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