What is the Correct Way to Find Eigenvalues and Eigenvectors of a Matrix?

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SUMMARY

The correct method to find the eigenvalues and eigenvectors of the matrix A = [-4 4 8; 0 0 -10; 0 0 2] involves calculating the characteristic polynomial by setting A - λI = 0. The eigenvalues determined from this calculation are λ = 0 (with multiplicity 2) and λ = 1. The corresponding eigenvectors are (1, 1, 0) for λ = 0 and (1, 0, 0) for λ = 1. It is crucial not to reduce the matrix before finding the eigenvalues, as this alters the results except for the zero eigenvalue.

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  • Understanding of eigenvalues and eigenvectors
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Find the eigenvalues and corresponding eigenvector of the matrix.
A=
[-4 4 8 ]
[0 0 -10]
[0 0 2 ]

[1 -1 0]
~ [0 0 1 ]
[0 0 0 ]

I calculated by A = -\lambdaI

So,

[1-lamda -1 0 ]
[0 -lamda 1]
[0 0 -lamda]

so, lamda = 0,0, and 1

So I got

1st eigen value: 0 eigen vector (1,1,0)
2nd eigen value: 0 eigen vector (1,1,0)
3rd eigen value: 1 eigen vector (1,0,0)

1st and 2nd values were right, but third one was wrong.
I tried several times, and I always get 1(1,0,0)

What do i need to do ?
thanks
 
Physics news on Phys.org
if you reduce the matrix, you change the eigenvalues, except for 0. don't reduce the matrix, find the characteristic polynomial of the original A.
 

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