Math Problem Statement

For matrix A, what is the characteristic polynomial and the eigenvector values.

Solution

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

  1. Compute the characteristic polynomial: The characteristic polynomial of a matrix AA is given by det(AλI)\det(A - \lambda I), where λ\lambda is a scalar and II is the identity matrix.

  2. Solve for the eigenvalues: The eigenvalues are the roots of the characteristic polynomial.

Given the matrix A=[2763]A = \begin{bmatrix} 2 & -7 \\ -6 & 3 \end{bmatrix}:

Step 1: Compute the Characteristic Polynomial

The characteristic polynomial is found by calculating the determinant of AλIA - \lambda I:

AλI=[2λ763λ]A - \lambda I = \begin{bmatrix} 2 - \lambda & -7 \\ -6 & 3 - \lambda \end{bmatrix}

The determinant of this matrix is:

det(AλI)=(2λ)(3λ)(7)(6)\det(A - \lambda I) = (2 - \lambda)(3 - \lambda) - (-7)(-6)

=(2λ)(3λ)42= (2 - \lambda)(3 - \lambda) - 42

=65λ+λ242= 6 - 5\lambda + \lambda^2 - 42

=λ25λ36= \lambda^2 - 5\lambda - 36

So, the characteristic polynomial is:

λ25λ36\lambda^2 - 5\lambda - 36

Step 2: Solve for the Eigenvalues

To find the eigenvalues, we solve the characteristic polynomial:

λ25λ36=0\lambda^2 - 5\lambda - 36 = 0

Using the quadratic formula λ=b±b24ac2a\lambda = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}, where a=1a = 1, b=5b = -5, and c=36c = -36:

λ=(5)±(5)24(1)(36)2(1)\lambda = \frac{-(-5) \pm \sqrt{(-5)^2 - 4(1)(-36)}}{2(1)}

=5±25+1442= \frac{5 \pm \sqrt{25 + 144}}{2}

=5±1692= \frac{5 \pm \sqrt{169}}{2}

=5±132= \frac{5 \pm 13}{2}

Thus, the eigenvalues are:

λ1=5+132=9\lambda_1 = \frac{5 + 13}{2} = 9 λ2=5132=4\lambda_2 = \frac{5 - 13}{2} = -4

Eigenvalues

The eigenvalues of the matrix AA are λ1=9\lambda_1 = 9 and λ2=4\lambda_2 = -4.

If you need any further details or have questions, feel free to ask!

Here are 8 related questions to explore further:

  1. How do you find the eigenvectors corresponding to each eigenvalue?
  2. What is the geometric interpretation of eigenvalues and eigenvectors?
  3. How can you verify if a given vector is an eigenvector of a matrix?
  4. What are the properties of diagonalizable matrices?
  5. How do you compute the determinant of a matrix?
  6. How does the trace of a matrix relate to its eigenvalues?
  7. What is the significance of the characteristic polynomial in linear algebra?
  8. How do eigenvalues affect the stability of a system of differential equations?

Tip: To find the eigenvectors, substitute each eigenvalue back into the equation (AλI)v=0(A - \lambda I)v = 0 and solve for the vector vv.

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Math Problem Analysis

Mathematical Concepts

Matrix Algebra
Eigenvalues
Characteristic Polynomial
Determinants

Formulas

Characteristic polynomial formula
Quadratic formula

Theorems

Eigenvalue theorem

Suitable Grade Level

Advanced College Level