Finding the eigenvectors of a 2nd multiplicity engenvalue

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Homework Help Overview

The discussion revolves around finding the eigenvectors of a given matrix with a focus on the eigenvalue of multiplicity 2. Participants are exploring the implications of having multiple eigenvectors associated with this eigenvalue.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the eigenvalues and eigenvectors derived from the matrix, specifically questioning the nature of the eigenvectors corresponding to the eigenvalue with multiplicity 2. There is an exploration of whether specific vectors, such as (1,1,2), can be considered valid eigenvectors.

Discussion Status

The discussion is active, with participants acknowledging the existence of multiple valid eigenvectors for the eigenvalue of 3. There is recognition that any linear combination of the eigenvectors can also serve as valid solutions, indicating a productive exploration of the topic.

Contextual Notes

Participants are considering the implications of having a two-dimensional space of eigenvectors for the eigenvalue of 3, leading to questions about the uniqueness of the eigenbasis.

xdrgnh
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Homework Statement


I'm given this matrice 2 1 0
1 2 0
0 0 3
and I need to find it's eigenvectors



Homework Equations





The Attempt at a Solution



So I get the eigenvalues to be 1,3,3 with 3 being the one with multiplicity of 2. For the eigenvector for 1 I get 1,-1,0 and for 3 I get 1,1,1 but here is the problem. For the other eigen vector for 3 the answer can be anything that satisfies x1=x2
x2=x1
x3=x3

so can something like 1,1,2 be the answer?
 
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xdrgnh said:

Homework Statement


I'm given this matrice 2 1 0
1 2 0
0 0 3
and I need to find it's eigenvectors



Homework Equations





The Attempt at a Solution



So I get the eigenvalues to be 1,3,3 with 3 being the one with multiplicity of 2. For the eigenvector for 1 I get 1,-1,0 and for 3 I get 1,1,1 but here is the problem. For the other eigen vector for 3 the answer can be anything that satisfies x1=x2
x2=x1
x3=x3

so can something like 1,1,2 be the answer?

Sure it could. Try it out if you are unsure. There are a lot of choices for specifying the eigenvectors. Any linear combination of 1,1,1 and 1,1,2 will also be an eigenvector with eigenvalue 3.
 
But wouldn't that mean there is no one definitive eigenbasis?
 
xdrgnh said:
But wouldn't that mean there is no one definitive eigenbasis?

Sure it would. There never is. You have a two dimensional space of eigenvectors with eigenvalue 3. There are lots of ways to choose a basis. I wouldn't call any of them 'definitive'.
 

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