Example: Find the eigenvalues and the eigenvectors of the matrix A = |
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From the eigenvalues equation we get the characteristic polynomial: |
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The eigenvalues are the roots of the characteristic polynomial, and are:
− 2, − 2, 4 this values are the diagonal values and has the same determinant
value as matrix A. In order to find the eigenvectors, substitute first solution
λ =− 2 into the characteristic matrix, the result is:
Those equations reduce to one independent equation: |
x − y + z = 0 |
Choose arbitrary y = 0 to receive the first eigenvector |
x = 1, y = 0, z = − 1 |
Choose arbitrary z = 0 to get the second vector: |
x = 1, y = 1, z = 0 |
Perform the same process with the third solution λ = 4 to get:
The result is two independent equations: |
x + y − z = 0 and 2y − z = 0 |
Choose arbitrary y = 1 to receive the vector |
x = 1, y = 1, z = 2 |
The three eigenvectors are: |
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We can see that the result is matching to the definition of the eigenvectors and eigenvalues:
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