Math Problem Statement

What are the eigenvectors?

Solution

Let's find the eigenvectors corresponding to the eigenvalues λ1=2+2i\lambda_1 = 2 + 2i and λ2=22i\lambda_2 = 2 - 2i.

Step 1: Eigenvector for λ1=2+2i\lambda_1 = 2 + 2i

We need to solve the equation:

(Aλ1I)v1=0(A - \lambda_1 I) \mathbf{v}_1 = 0

Substituting λ1=2+2i\lambda_1 = 2 + 2i into the matrix:

Aλ1I=(1(2+2i)513(2+2i))=(12i5112i)A - \lambda_1 I = \begin{pmatrix} 1-(2+2i) & -5 \\ 1 & 3-(2+2i) \end{pmatrix} = \begin{pmatrix} -1-2i & -5 \\ 1 & 1-2i \end{pmatrix}

Now, we solve the system:

(12i5112i)(v11v12)=(00)\begin{pmatrix} -1-2i & -5 \\ 1 & 1-2i \end{pmatrix} \begin{pmatrix} v_{11} \\ v_{12} \end{pmatrix} = \begin{pmatrix} 0 \\ 0 \end{pmatrix}

This leads to the following two equations:

(-1 - 2i)v_{11} - 5v_{12} = 0 \\ v_{11} + (1 - 2i)v_{12} = 0 \end{cases}$$ From the first equation: $$v_{11} = \frac{-5v_{12}}{-1-2i} = \frac{5v_{12}}{1+2i}$$ To simplify $$\frac{5}{1+2i}$$, multiply numerator and denominator by the complex conjugate of the denominator: $$\frac{5}{1+2i} \cdot \frac{1-2i}{1-2i} = \frac{5(1-2i)}{(1+2i)(1-2i)} = \frac{5(1-2i)}{1 + 4} = \frac{5 - 10i}{5} = 1 - 2i$$ So, $$v_{11} = (1 - 2i)v_{12}$$ Thus, the eigenvector corresponding to $$\lambda_1 = 2 + 2i$$ can be written as: $$\mathbf{v}_1 = v_{12} \begin{pmatrix} 1 - 2i \\ 1 \end{pmatrix}$$ For simplicity, let $$v_{12} = 1$$. Then the eigenvector is: $$\mathbf{v}_1 = \begin{pmatrix} 1 - 2i \\ 1 \end{pmatrix}$$ ### Step 2: Eigenvector for $$\lambda_2 = 2 - 2i$$ Similarly, for $$\lambda_2 = 2 - 2i$$, we solve: $$(A - \lambda_2 I) \mathbf{v}_2 = 0$$ Substituting $$\lambda_2 = 2 - 2i$$ into the matrix: $$A - \lambda_2 I = \begin{pmatrix} 1-(2-2i) & -5 \\ 1 & 3-(2-2i) \end{pmatrix} = \begin{pmatrix} -1+2i & -5 \\ 1 & 1+2i \end{pmatrix}$$ Now, solve the system: $$\begin{pmatrix} -1+2i & -5 \\ 1 & 1+2i \end{pmatrix} \begin{pmatrix} v_{21} \\ v_{22} \end{pmatrix} = \begin{pmatrix} 0 \\ 0 \end{pmatrix}$$ From the first equation: $$v_{21} = \frac{-5v_{22}}{-1+2i} = \frac{5v_{22}}{1-2i}$$ Simplifying $$\frac{5}{1-2i}$$: $$\frac{5}{1-2i} \cdot \frac{1+2i}{1+2i} = \frac{5(1+2i)}{(1-2i)(1+2i)} = \frac{5(1+2i)}{1 + 4} = \frac{5 + 10i}{5} = 1 + 2i$$ So, $$v_{21} = (1 + 2i)v_{22}$$ Thus, the eigenvector corresponding to $$\lambda_2 = 2 - 2i$$ is: $$\mathbf{v}_2 = v_{22} \begin{pmatrix} 1 + 2i \\ 1 \end{pmatrix}$$ For simplicity, let $$v_{22} = 1$$. Then the eigenvector is: $$\mathbf{v}_2 = \begin{pmatrix} 1 + 2i \\ 1 \end{pmatrix}$$ ### Summary - The eigenvector corresponding to $$\lambda_1 = 2 + 2i$$ is $$\mathbf{v}_1 = \begin{pmatrix} 1 - 2i \\ 1 \end{pmatrix}$$. - The eigenvector corresponding to $$\lambda_2 = 2 - 2i$$ is $$\mathbf{v}_2 = \begin{pmatrix} 1 + 2i \\ 1 \end{pmatrix}$$. Do you have any more questions or need further clarification? Here are 5 related questions: 1. How do eigenvectors help in solving systems of differential equations? 2. What is the significance of complex eigenvectors in the solution? 3. How do you interpret the real and imaginary parts of the eigenvectors? 4. Can you have multiple linearly independent eigenvectors for a single eigenvalue? 5. How would the solution look if the eigenvalues were purely real? **Tip:** When dealing with complex eigenvalues, it is often helpful to express the solution in terms of real-valued functions using Euler's formula.

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Math Problem Analysis

Mathematical Concepts

Eigenvalues
Eigenvectors
Complex numbers
Matrix operations

Formulas

Eigenvalue equation (A - λI)v = 0

Theorems

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Suitable Grade Level

Advanced undergraduate level