Differential Equations - Eigenvalues and Eigenfunctions

In summary, the student is looking for guidance on how to proceed with a homework problem that they are struggling with. They say that they do not understand what they are supposed to do and that their textbook is not helping.
  • #1
solomar
6
0

Homework Statement


Find the eigenvalues and the eigenfunctions for
x^2y"+2xy'+λy = 0 y(1) = 0, y(e^2) = 0


Homework Equations



See problem

The Attempt at a Solution


My book has one paragraph on this that does not help me. I tried using an auxiliary equation and solving for lambda.
I get (m+√λ)^2 a real number with duplicity two. I don't know what to do with this or if this is even the right first step. The SINGLE paragraph on this doesn't explain anything (it's practically a side note)

I would appreciate some guidance. There are two problems like this on the take home quiz and we didn't go over it in class so I am very lost and confused.
Also I've been pounding my head over this with my directionless fury. Help subside my hate!

Thanks for your time everyone!
 
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  • #2
You mean "multiplicity" 2 ("duplicity" has a completely different meaning!). And, while you say you "get (m+√λ)^2" you don't say what that is supposed to be- particularly since there is no "m" in the problem. Please show how you got that.

(I'm not sure what you mean by "m" but I get nothing like that. It looks to me like [itex]\lambda[/itex] will have to be larger than 1/4 in order to get a non-trivial function that is 0 for two different x values.)
 
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  • #3
I got it from changing the DE into
m^2 + 2m + λ
I did the "m" thing because in the previous chapters to solve some equations I would solve the associated homogeneous DE and use the value of m to determine the structure of the general solution.
It's the only step I have made and I feel like even that is wrong. I don't know what to do with the initial values or anything...
Thanks for clearing up the duplicity multiplicity thing, you're right :)

My problem is a complete lack of understanding of what I am supposed to do, and my textbook is not helping haha...
 

What is a differential equation?

A differential equation is an equation that relates a function, its derivatives, and independent variables. It is used to model and describe various physical, biological, and economic phenomena.

What are eigenvalues and eigenfunctions?

Eigenvalues and eigenfunctions are a pair of special values and corresponding functions that arise in the solution of differential equations. The eigenvalues represent the possible values of a physical quantity, while the eigenfunctions describe the corresponding wave or oscillation patterns.

Why are eigenvalues and eigenfunctions important?

Eigenvalues and eigenfunctions are important because they allow us to describe and understand the behavior of physical systems. They are used in a wide range of fields, including quantum mechanics, signal processing, and vibration analysis.

How do you find eigenvalues and eigenfunctions?

To find eigenvalues and eigenfunctions, you need to solve the characteristic equation associated with the differential equation. This involves finding the roots of the characteristic polynomial and using them to determine the corresponding eigenvalues. The eigenfunctions can then be obtained by plugging in the eigenvalues into the original differential equation.

What is the significance of eigenvalues and eigenfunctions in differential equations?

Eigenvalues and eigenfunctions are significant in differential equations because they provide a systematic way to solve complex problems. They allow us to reduce a higher-order differential equation into a simpler form, making it easier to analyze and understand the behavior of the system.

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