Compute the eigenvalues and bases of eigenspaces of the following matrix -2 1 4 4 1 -4 -1 1 A = 3

Algebra and Trigonometry (6th Edition)
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ChapterP: Prerequisites: Fundamental Concepts Of Algebra
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Problem 1MCCP: In Exercises 1-25, simplify the given expression or perform the indicated operation (and simplify,...
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**Computing Eigenvalues and Bases of Eigenspaces**

To determine the eigenvalues and bases of eigenspaces for a given matrix \( A \), follow these steps:

Given matrix:

\[
A = \begin{bmatrix}
-2 & 1 & 4 \\
4 & 1 & -4 \\
-1 & 1 & 3 
\end{bmatrix}
\]

1. **Compute the Eigenvalues**:
   
   Eigenvalues (\(\lambda\)) of a matrix \( A \) are found by solving the characteristic equation:
   
   \[
   \det(A - \lambda I) = 0
   \]
   
   Here, \( I \) is the identity matrix of the same dimension as \( A \), and \( \det \) denotes the determinant.

2. **Construct the Matrix \( A - \lambda I \)**:
   
   \[
   A - \lambda I = \begin{bmatrix}
   -2-\lambda & 1 & 4 \\
   4 & 1-\lambda & -4 \\
   -1 & 1 & 3-\lambda 
   \end{bmatrix}
   \]

3. **Compute the Determinant of \( A - \lambda I \)**:

   \[
   \det(A - \lambda I) = \begin{vmatrix}
   -2-\lambda & 1 & 4 \\
   4 & 1-\lambda & -4 \\
   -1 & 1 & 3-\lambda 
   \end{vmatrix}
   \]

   Calculate this determinant to find the characteristic polynomial and set it equal to zero to solve for the eigenvalues.

4. **Solve for the Eigenvalues**: 

   Find the roots of the characteristic polynomial obtained from the determinant calculation. These roots are the eigenvalues \( \lambda_1, \lambda_2, \lambda_3 \).

5. **Find the Eigenspaces**:

   For each eigenvalue \(\lambda_i\), solve the system of linear equations:

   \[
   (A - \lambda_i I)\mathbf{x} = \mathbf{0}
   \]

   where \(\mathbf{x}\) is the eigenvector corresponding to \(\lambda_i\).

6. **Form the Basis for Each Eigenspace**:

   The nontrivial solutions to the above system give the
Transcribed Image Text:**Computing Eigenvalues and Bases of Eigenspaces** To determine the eigenvalues and bases of eigenspaces for a given matrix \( A \), follow these steps: Given matrix: \[ A = \begin{bmatrix} -2 & 1 & 4 \\ 4 & 1 & -4 \\ -1 & 1 & 3 \end{bmatrix} \] 1. **Compute the Eigenvalues**: Eigenvalues (\(\lambda\)) of a matrix \( A \) are found by solving the characteristic equation: \[ \det(A - \lambda I) = 0 \] Here, \( I \) is the identity matrix of the same dimension as \( A \), and \( \det \) denotes the determinant. 2. **Construct the Matrix \( A - \lambda I \)**: \[ A - \lambda I = \begin{bmatrix} -2-\lambda & 1 & 4 \\ 4 & 1-\lambda & -4 \\ -1 & 1 & 3-\lambda \end{bmatrix} \] 3. **Compute the Determinant of \( A - \lambda I \)**: \[ \det(A - \lambda I) = \begin{vmatrix} -2-\lambda & 1 & 4 \\ 4 & 1-\lambda & -4 \\ -1 & 1 & 3-\lambda \end{vmatrix} \] Calculate this determinant to find the characteristic polynomial and set it equal to zero to solve for the eigenvalues. 4. **Solve for the Eigenvalues**: Find the roots of the characteristic polynomial obtained from the determinant calculation. These roots are the eigenvalues \( \lambda_1, \lambda_2, \lambda_3 \). 5. **Find the Eigenspaces**: For each eigenvalue \(\lambda_i\), solve the system of linear equations: \[ (A - \lambda_i I)\mathbf{x} = \mathbf{0} \] where \(\mathbf{x}\) is the eigenvector corresponding to \(\lambda_i\). 6. **Form the Basis for Each Eigenspace**: The nontrivial solutions to the above system give the
**Problem Statement**

Compute the eigenvalues and bases of eigenspaces of the following matrix:

\[ 
A = \begin{bmatrix} 
-2 & -2 \\ 
6 & 5 
\end{bmatrix}. 
\]

**Solution**

To find the eigenvalues \(\lambda\) of the matrix \(A\), we need to solve the characteristic equation \(\det(A - \lambda I) = 0\), where \(I\) is the identity matrix of the same dimension as \(A\).

1. Construct the matrix \(A - \lambda I\):
\[ 
A - \lambda I = \begin{bmatrix} 
-2 - \lambda & -2 \\ 
6 & 5 - \lambda 
\end{bmatrix}. 
\]

2. Compute the determinant of the matrix \(A - \lambda I\):

\[ 
\det(A - \lambda I) = \begin{vmatrix} 
-2 - \lambda & -2 \\ 
6 & 5 - \lambda 
\end{vmatrix} = (-2 - \lambda)(5 - \lambda) - (-2)(6).
\]

3. Expand the determinant:

\[ 
(-2 - \lambda)(5 - \lambda) + 12 = \lambda^2 - 3\lambda - 10 + 12 = \lambda^2 - 3\lambda + 2.
\]

4. Set the determinant equal to zero:

\[ 
\lambda^2 - 3\lambda + 2 = 0.
\]

5. Solve the quadratic equation for \(\lambda\):

\[ 
(\lambda - 1)(\lambda - 2) = 0.
\]

6. Therefore, the eigenvalues are \(\lambda_1 = 1\) and \(\lambda_2 = 2\).

**Finding Eigenspaces**

Next, we need to find the eigenvectors corresponding to each eigenvalue to determine the bases of the eigenspaces.

1. For \(\lambda_1 = 1\):

\[ 
A - \lambda_1 I = \begin{bmatrix} 
-2 - 1 & -2 \\ 
6 & 5 - 1 
\end{bmatrix} = \begin{bmatrix} 
-3 & -2 \\ 
6 & 4 
\end{bmatrix}. 
\]
Transcribed Image Text:**Problem Statement** Compute the eigenvalues and bases of eigenspaces of the following matrix: \[ A = \begin{bmatrix} -2 & -2 \\ 6 & 5 \end{bmatrix}. \] **Solution** To find the eigenvalues \(\lambda\) of the matrix \(A\), we need to solve the characteristic equation \(\det(A - \lambda I) = 0\), where \(I\) is the identity matrix of the same dimension as \(A\). 1. Construct the matrix \(A - \lambda I\): \[ A - \lambda I = \begin{bmatrix} -2 - \lambda & -2 \\ 6 & 5 - \lambda \end{bmatrix}. \] 2. Compute the determinant of the matrix \(A - \lambda I\): \[ \det(A - \lambda I) = \begin{vmatrix} -2 - \lambda & -2 \\ 6 & 5 - \lambda \end{vmatrix} = (-2 - \lambda)(5 - \lambda) - (-2)(6). \] 3. Expand the determinant: \[ (-2 - \lambda)(5 - \lambda) + 12 = \lambda^2 - 3\lambda - 10 + 12 = \lambda^2 - 3\lambda + 2. \] 4. Set the determinant equal to zero: \[ \lambda^2 - 3\lambda + 2 = 0. \] 5. Solve the quadratic equation for \(\lambda\): \[ (\lambda - 1)(\lambda - 2) = 0. \] 6. Therefore, the eigenvalues are \(\lambda_1 = 1\) and \(\lambda_2 = 2\). **Finding Eigenspaces** Next, we need to find the eigenvectors corresponding to each eigenvalue to determine the bases of the eigenspaces. 1. For \(\lambda_1 = 1\): \[ A - \lambda_1 I = \begin{bmatrix} -2 - 1 & -2 \\ 6 & 5 - 1 \end{bmatrix} = \begin{bmatrix} -3 & -2 \\ 6 & 4 \end{bmatrix}. \]
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