Variation of parameters- 2nd order linear equation

Now, the characteristic equation is s^2 - s + \frac14 = 0. This factors into a perfect square, (s - \frac12)^2 = 0. Hence, the homogeneous solution is y_h = Ae^{t/2} + Bte^{t/2}. Now, for the particular solution, let's try y_p = Ce^{t/2} for a constant C. Then, plugging back into the original equation, we find that C = 4. Therefore, y_p = 4e^{t/2} works. Hence, the general solution isy = y_h + y_p = Ae^{t/2} + Bte^{
  • #1
hahaha158
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Homework Statement


solve 4y''-4y'+y=16et/2


Homework Equations



v1= -∫ y2g/w
v2= ∫ y1g/w

The Attempt at a Solution



http://imgur.com/gxXlfdH

the correct answer is 2t^2 e^(t/2) instead of what i have though, i am not sure what i am doing wrong?
 
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  • #2
hahaha158 said:

Homework Statement


solve 4y''-4y'+y=16et/2


Homework Equations



v1= -∫ y2g/w
v2= ∫ y1g/w

The Attempt at a Solution



http://imgur.com/gxXlfdH

the correct answer is 2t^2 e^(t/2) instead of what i have though, i am not sure what i am doing wrong?

You need to divide by the coefficient of [itex]y''[/itex] before you start:
[tex]
y'' - y' + \frac14 y = 4e^{t/2} \equiv g(t).
[/tex]
 

FAQ: Variation of parameters- 2nd order linear equation

1. What is the concept of variation of parameters in solving 2nd order linear equations?

The variation of parameters method is a technique used to find a particular solution to a 2nd order linear differential equation. It involves replacing the constants in the homogeneous solution with functions and then solving for those functions.

2. How is the variation of parameters method different from other methods of solving differential equations?

The variation of parameters method is different from other methods, such as the method of undetermined coefficients, in that it allows for a more general solution by incorporating arbitrary functions instead of just constants. This can be especially useful when dealing with non-homogeneous differential equations.

3. What are the steps involved in using the variation of parameters method?

The first step is to solve the corresponding homogeneous equation and find the general solution. Then, we find the particular solution by replacing the constants in the general solution with functions and setting up a system of equations. Finally, we solve for the functions and substitute them back into the particular solution.

4. Can the variation of parameters method be used for non-linear differential equations?

No, the variation of parameters method is only applicable to 2nd order linear differential equations. For non-linear equations, other methods such as the Euler method or Runge-Kutta methods may be used.

5. Are there any limitations or drawbacks to using the variation of parameters method?

One limitation of the variation of parameters method is that it can become quite complex and tedious, especially when dealing with higher order differential equations. It also requires knowledge of solving systems of equations, which can be challenging for some. Additionally, it may not always yield a closed-form solution, which can be difficult to work with in some cases.

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