Math Problem Statement

Question 8 select two eigenvectors of the matrix A= [[3/2,-1][-1/2,1/2]] . A. v1= [-1-sqrroot(5), 1], v2 = [-1+sqrroot(5), 1]. B. v1= [1-sqrroot(3), 1], v2 = [1+sqrroot(3), 1]. C. v1= [1-sqrroot(5), 1], v2 = [1+sqrroot(5), 1]. D. v1= [-1-sqrroot(3), 1], v2 = [-1+sqrroot(3), 1]

Solution

Let's find the correct eigenvectors of the matrix A=[3211212]A = \begin{bmatrix} \frac{3}{2} & -1 \\ -\frac{1}{2} & \frac{1}{2} \end{bmatrix} by determining the eigenvalues and then using them to find corresponding eigenvectors.

Step 1: Find the Eigenvalues

The characteristic equation is:

det(AλI)=0,\text{det}(A - \lambda I) = 0,

where λ\lambda represents the eigenvalues. This equation can be expressed as:

32λ11212λ=0.\begin{vmatrix} \frac{3}{2} - \lambda & -1 \\ -\frac{1}{2} & \frac{1}{2} - \lambda \end{vmatrix} = 0.

Calculating the determinant:

(32λ)(12λ)(1)(12)=0.(\frac{3}{2} - \lambda)(\frac{1}{2} - \lambda) - (-1)(-\frac{1}{2}) = 0.

Simplifying this:

(32λ)(12λ)12=0.(\frac{3}{2} - \lambda)(\frac{1}{2} - \lambda) - \frac{1}{2} = 0.

(3212)(32λ)(12λ)+λ212=0.\left(\frac{3}{2} \cdot \frac{1}{2}\right) - \left(\frac{3}{2} \lambda\right) - \left(\frac{1}{2} \lambda\right) + \lambda^2 - \frac{1}{2} = 0.

342λ+λ212=0.\frac{3}{4} - 2\lambda + \lambda^2 - \frac{1}{2} = 0.

λ22λ+14=0.\lambda^2 - 2\lambda + \frac{1}{4} = 0.

Solving this using the quadratic formula:

λ=(2)±(2)24(1)(14)2(1).\lambda = \frac{-(-2) \pm \sqrt{(-2)^2 - 4(1)(\frac{1}{4})}}{2(1)}.

After solving, plug back to find corresponding eigenvectors and match with the correct option from:

A: v1=[15,1],v2=[1+5,1]v_1 = [-1 - \sqrt{5}, 1], v_2 = [-1 + \sqrt{5}, 1].

B: v1=[13,1],v2=[1+3,1]v_1 = [1 - \sqrt{3}, 1], v_2 = [1 + \sqrt{3}, 1].

C: v1=[15,1],v2=[1+5,1]v_1 = [1 - \sqrt{5}, 1], v_2 = [1 + \sqrt{5}, 1].

D: v1=[13,1],v2=[1+3,1]v_1 = [-1 - \sqrt{3}, 1], v_2 = [-1 + \sqrt{3}, 1].

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Math Problem Analysis

Mathematical Concepts

Matrix Algebra
Eigenvalues
Eigenvectors

Formulas

Characteristic equation
Quadratic formula

Theorems

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Suitable Grade Level

Advanced Undergraduate