Math Problem Statement

Find the eigenvalues and eigenvectors of the matrix A = [[1, 0, -1], [1, 2, 1], [2, 2, 3]].

Solution

To find the eigenvalues and eigenvectors of the matrix AA, we need to follow these steps:

1. Find the Eigenvalues:

  • The eigenvalues λ\lambda are found by solving the characteristic equation, which is determined from the determinant of the matrix AλI=0A - \lambda I = 0, where II is the identity matrix of the same size as AA.

Given matrix A=(101121223)A = \begin{pmatrix} 1 & 0 & -1 \\ 1 & 2 & 1 \\ 2 & 2 & 3 \end{pmatrix}, let's compute the characteristic equation.

det(AλI)=det((101121223)λ(100010001))\text{det}(A - \lambda I) = \text{det} \left( \begin{pmatrix} 1 & 0 & -1 \\ 1 & 2 & 1 \\ 2 & 2 & 3 \end{pmatrix} - \lambda \begin{pmatrix} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{pmatrix} \right)

=det((1λ0112λ1223λ))= \text{det} \left( \begin{pmatrix} 1-\lambda & 0 & -1 \\ 1 & 2-\lambda & 1 \\ 2 & 2 & 3-\lambda \end{pmatrix} \right)

Now, let's compute this determinant.

2. Find the Eigenvectors:

  • For each eigenvalue λi\lambda_i, solve the system (AλiI)v=0(A - \lambda_i I) \mathbf{v} = 0 to find the corresponding eigenvector v\mathbf{v}.

I'll perform these calculations now.### Results:

The eigenvalues of the matrix AA are:

λ1=1,λ2=2,λ3=3\lambda_1 = 1, \quad \lambda_2 = 2, \quad \lambda_3 = 3

The corresponding eigenvectors are:

  1. For λ1=1\lambda_1 = 1: v1=(110)\mathbf{v}_1 = \begin{pmatrix} -1 \\ 1 \\ 0 \end{pmatrix}

  2. For λ2=2\lambda_2 = 2: v2=(1121)\mathbf{v}_2 = \begin{pmatrix} -1 \\ \frac{1}{2} \\ 1 \end{pmatrix}

  3. For λ3=3\lambda_3 = 3: v3=(12121)\mathbf{v}_3 = \begin{pmatrix} -\frac{1}{2} \\ \frac{1}{2} \\ 1 \end{pmatrix}

Would you like more details on any of these steps, or do you have any questions?

Here are 5 related questions:

  1. How do you verify that a given vector is indeed an eigenvector of a matrix?
  2. Can a matrix have complex eigenvalues and eigenvectors?
  3. What is the geometric significance of eigenvalues and eigenvectors?
  4. How does the determinant of a matrix relate to its eigenvalues?
  5. What are the conditions for a matrix to be diagonalizable?

Tip: Eigenvalues provide insight into the behavior of linear transformations, such as scaling along certain directions (eigenvectors). Understanding their calculation can be crucial in various fields, including physics, engineering, and machine learning.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Eigenvalues and Eigenvectors
Matrices

Formulas

Characteristic equation: det(A - λI) = 0
Eigenvector equation: (A - λI)v = 0

Theorems

Eigenvalue-Eigenvector Theorem

Suitable Grade Level

Undergraduate