Math Problem Statement

Question 9

Form the matrix

C whose left column is the vector

v1

and whose right column is

v2

from immediately above.

By calculating

D=C^-1 AC or by using another method, find the diagonal matrix D.

Solution

To solve this problem, let's break it down into steps:

  1. Form the Matrix CC:

    • Given that matrix CC is composed of the vectors v1v_1 and v2v_2, the left column of CC will be v1v_1 and the right column will be v2v_2.
    • Suppose v1=[a1b1]v_1 = \begin{bmatrix} a_1 \\ b_1 \end{bmatrix} and v2=[a2b2]v_2 = \begin{bmatrix} a_2 \\ b_2 \end{bmatrix}.
    • Then, the matrix CC will be: a_1 & a_2 \\ b_1 & b_2 \end{bmatrix}$$
  2. Find the Inverse of CC (i.e., C1C^{-1}):

    • The inverse of a 2x2 matrix C=[pqrs]C = \begin{bmatrix} p & q \\ r & s \end{bmatrix} is given by: C1=1det(C)[sqrp]C^{-1} = \frac{1}{\text{det}(C)} \begin{bmatrix} s & -q \\ -r & p \end{bmatrix}
    • Where the determinant det(C)\text{det}(C) is psqrps - qr.
  3. Calculate the Matrix D=C1ACD = C^{-1}AC:

    • To diagonalize matrix AA, we multiply it by C1C^{-1} on the left and by CC on the right.
    • The result DD will be the diagonal matrix where the diagonal elements are the eigenvalues of AA.
  4. Alternative Method:

    • If we have the eigenvalues λ1\lambda_1 and λ2\lambda_2 of AA, the diagonal matrix DD can also be directly written as: \lambda_1 & 0 \\ 0 & \lambda_2 \end{bmatrix}$$

Example Calculation (Hypothetical Values)

Let's assume specific values for v1v_1, v2v_2, and AA for demonstration.

Suppose: v1=[12],v2=[34],A=[5678]v_1 = \begin{bmatrix} 1 \\ 2 \end{bmatrix}, \quad v_2 = \begin{bmatrix} 3 \\ 4 \end{bmatrix}, \quad A = \begin{bmatrix} 5 & 6 \\ 7 & 8 \end{bmatrix} Then: C=[1324]C = \begin{bmatrix} 1 & 3 \\ 2 & 4 \end{bmatrix} The determinant of CC: det(C)=(1)(4)(3)(2)=46=2\text{det}(C) = (1)(4) - (3)(2) = 4 - 6 = -2 The inverse C1C^{-1} is: C1=12[4321]=[21.510.5]C^{-1} = \frac{1}{-2} \begin{bmatrix} 4 & -3 \\ -2 & 1 \end{bmatrix} = \begin{bmatrix} -2 & 1.5 \\ 1 & -0.5 \end{bmatrix} Now, calculate D=C1ACD = C^{-1}AC.

If you have specific vectors v1v_1 and v2v_2, and a matrix AA, I can calculate the exact matrix DD for you.

Would you like to provide those values or do you have any questions?


Relative Questions:

  1. How is the determinant of a matrix used in finding its inverse?
  2. Can every matrix be diagonalized? Why or why not?
  3. What are eigenvalues and eigenvectors, and how are they related to matrix diagonalization?
  4. Why is the diagonalization of a matrix useful in mathematical analysis?
  5. How do the values of v1v_1 and v2v_2 affect the matrix CC and the resulting diagonal matrix DD?

Tip: Diagonalizing a matrix is a powerful tool in simplifying matrix operations, particularly for finding powers of matrices or solving differential equations.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Matrix Inversion
Diagonalization

Formulas

Matrix inverse formula
Diagonalization of matrices

Theorems

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Suitable Grade Level

Advanced Mathematics