Solving DE Using Variation of Parameters & Given Solution

In summary, the conversation discusses solving the differential equation (1-x)y''+xy'-y=(1-x)^2 using the fact that y=x is a solution when the right hand side is 0. The person is considering using the variation of parameters method but is unsure since they only have one complementary solution. They are advised to use the reduction of order technique by letting y=xv. This approach is successful in obtaining the general solution.
  • #1
fluidistic
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Homework Statement


I must solve [itex](1-x)y''+xy'-y=(1-x)^2[/itex] knowing that y=x is a solution if the right hand side is 0. I must use this fact in order to obtain the general solution to the DE


Homework Equations


Variation of parameters?


The Attempt at a Solution


I'm looking at http://tutorial.math.lamar.edu/Classes/DE/VariationofParameters.aspx and I think I need to use the Variation of parameters to solve the problem.
But I'm given only one complementary solution, not the two I would need. I really don't know how to proceed then...
What I did was rewrite the DE into [itex]y''+y' \left ( \frac{x}{1-x} \right )-y \left ( \frac{1}{1-x} \right ) =1-x[/itex].
Any tip will be appreciated, as usual.
 
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  • #2
Use Reduction of Order when you have only one solution. Just let y=xv and run it through the technique.
 
  • #3
jackmell said:
Use Reduction of Order when you have only one solution. Just let y=xv and run it through the technique.

Thanks, this worked out well.
 

1. What is the variation of parameters method for solving differential equations?

The variation of parameters method is a technique used to find a particular solution to a non-homogeneous linear differential equation. It involves using a known solution to the corresponding homogeneous equation to determine a particular solution.

2. When is the variation of parameters method used?

The variation of parameters method is used when the non-homogeneous term in a differential equation is not in the form of a simple function, such as a polynomial or exponential. It is also useful when the non-homogeneous term is a sum of multiple terms.

3. How do you use the variation of parameters method to solve a differential equation?

To use the variation of parameters method, you first find the general solution to the corresponding homogeneous equation. Then, you use this solution to determine the coefficients of the particular solution by setting up a system of equations and solving for the coefficients. Finally, you combine the homogeneous and particular solutions to get the general solution to the non-homogeneous equation.

4. Can the variation of parameters method be used for all types of differential equations?

No, the variation of parameters method can only be used for non-homogeneous linear differential equations. It cannot be used for non-linear equations or equations with non-constant coefficients.

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

Yes, one limitation is that the method can become very complicated and difficult to solve for certain types of non-homogeneous terms. Additionally, the method may not always yield a simple or closed-form solution, making it difficult to interpret or use in real-world applications.

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