How to Find Eigenvalues and Eigenvectors for 2x2 Matrices?

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Homework Help Overview

The discussion revolves around finding eigenvalues and eigenvectors for 2x2 matrices, specifically the matrices A=[0,0;0,8] and A=[-8,0;0,0]. Participants are exploring the process of determining eigenvectors associated with given eigenvalues.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to find eigenvectors by making guesses for one variable and deriving the other. Some participants question the validity of this guessing approach, suggesting that the process should not require guessing. Others clarify the distinction between finding eigenvectors for individual matrices versus a common eigenvector for both matrices.

Discussion Status

The discussion is ongoing, with participants providing guidance on the nature of eigenvalues and eigenvectors. There is an exploration of the original poster's understanding of the process, and some clarification on the definitions and expectations regarding eigenvectors.

Contextual Notes

There is a mention of the original question involving the eigenvalues of A=[1,0;0,9], with the eigenvalues identified as 1 and 9. The original poster expresses confusion regarding the resulting equations leading to zero eigenvectors, indicating a need for further exploration of the conditions under which eigenvectors can be non-zero.

richard7893
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Homework Statement


im trying to find the eigen vector for these 2 matrices: A=[0,0;0,8] AND A=[-8,0;0,0]


Homework Equations





The Attempt at a Solution


BACICALLY WHAT IM DOING IS "GUESSING" AT What x1, is then I am coming up wth the solution to x2 once I've made my guess for x1. how can i know for sure if my guyess is correct?
 
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What do you mean by your guesses? Finding eigenvectors and eigenvalues is a process that doesn't need guessing.
 
Also what do you mean by "the eigenvector for these matrices". Each matrix has two (obvious) eigenvalues and an infinite number of eigenvectors. Do you mean "find the eigenvectors of each matrix" or "find a vector that is an eigenvector for both matrices"?
 
I mean find the eigenvectors of each matrix. The original question is Find the eigenvals and eigenvecs of A=[1,0;0,9]. I know the eigvals are 1 and 9. However when I try to find the eigvec for lamda =1 and lamda = 9 respectively i get these matrices: when lamda =1 [0,0;0,8] and lamda =9 [-8,0;0,0]. For some reason I'm just thinking that eigenvector for both of these is 0 becase for instance in the mathrix when lamda =1 you get the eqn:
0x+8y=0 and 0x+0y=0. This is almost the same case for when lamda = 9. How do you find x and y to get the eigenvectors without them being 0 because there is no such thing as a 0 eigenvector.
 

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