/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 7 Show that any \(3 \times 3\) mat... [FREE SOLUTION] | 91影视

91影视

Show that any \(3 \times 3\) matrix of the form \\[ \left(\begin{array}{lll} a & 1 & 0 \\ 0 & a & 1 \\ 0 & 0 & b \end{array}\right) \\] is defective.

Short Answer

Expert verified
To show that the given $3 \times 3$ matrix \(A = \begin{pmatrix} a & 1 & 0 \\ 0 & a & 1 \\ 0 & 0 & b \end{pmatrix}\) is defective, we find its eigenvalues and eigenvectors. The eigenvalues are 位鈧 = a, with algebraic multiplicity 2, and 位鈧 = b, with algebraic multiplicity 1. Eigenvectors for 位鈧 are of the form \(v_1 = \begin{pmatrix} x \\ 0 \\ 0 \end{pmatrix}\) (one linearly independent eigenvector) and for 位鈧 are of the form \(v_2 = \begin{pmatrix} a - b \\ b - a \\ 1 \end{pmatrix}\) (one linearly independent eigenvector). Since there are only 2 linearly independent eigenvectors for this 3x3 matrix, it is defective.

Step by step solution

01

Find the eigenvalues of the matrix

First, we need to determine the eigenvalues of the given matrix. We will do this by solving the characteristic equation, which is given by the determinant of (A - 位I) where A is the matrix, 位 is the eigenvalue, and I is the identity matrix. Let the given matrix A be defined as: \( A = \begin{pmatrix} a & 1 & 0 \\ 0 & a & 1 \\ 0 & 0 & b \end{pmatrix} \) The determinant |A - 位I| is: \(|A - 位I|= \begin{vmatrix} a - 位 & 1 & 0 \\ 0 & a - 位 & 1 \\ 0 & 0 & b - 位 \end{vmatrix} \) Now, let's evaluate the determinant using the first row for cofactor expansion: \(|A - 位I|= (a - 位) \begin{vmatrix} a - 位 & 1 \\ 0 & b - 位 \end{vmatrix} = (a - 位)((a - 位)(b - 位) - 0) = (a - 位)^2 (b - 位)\) To find the eigenvalues, we find the roots of |A - 位I|: \(|A - 位I| = (a - 位)^2 (b - 位) = 0\) This equation has two distinct eigenvalues 位鈧 = a, and 位鈧 = b, with algebraic multiplicities of 2 and 1 respectively.
02

Determine the eigenvectors of the matrix

Now let's find the eigenvectors for each eigenvalue by solving (A - 位I)v = 0, where v is the eigenvector. a) 位鈧 = a (algebraic multiplicity 2) (A - aI)v = 0 \(\begin{pmatrix} 0 & 1 & 0 \\ 0 & 0 & 1 \\ 0 & 0 & b - a \end{pmatrix}\begin{pmatrix} x \\ y \\ z \end{pmatrix} = \begin{pmatrix} 0 \\ 0 \\ 0 \end{pmatrix}\) Row 1: \( y = 0 \) Row 2: \( z = 0 \) Row 3: \( (b - a)z = 0\) Since we are considering the case where 位鈧 = a, we have z = 0. Therefore, the only eigenvector corresponding to 位鈧 = a is \(v_1 = \begin{pmatrix} x \\ 0 \\ 0 \end{pmatrix}\), where x is any scalar. This indicates that 位鈧 has one linearly independent eigenvector. b) 位鈧 = b (algebraic multiplicity 1) (A - bI)v = 0 \(\begin{pmatrix} a - b & 1 & 0 \\ 0 & a - b & 1 \\ 0 & 0 & 0 \end{pmatrix}\begin{pmatrix} x \\ y \\ z \end{pmatrix} = \begin{pmatrix} 0 \\ 0 \\ 0 \end{pmatrix}\) Row 1: \( (a - b)x + y = 0 \) Row 2: \( (a - b)y + z = 0 \) Row 3: \( 0 = 0\) In this case, we get one eigenvector corresponding to 位鈧 = b. Let this eigenvector be \(v_2 = \begin{pmatrix} x \\ y \\ z \end{pmatrix} = \begin{pmatrix} a - b \\ b - a \\ 1 \end{pmatrix}\), which is the only linearly independent eigenvector.
03

Confirm that the matrix is defective

We found 2 distinct eigenvalues for the given 3x3 matrix. The eigenvalues 位鈧 = a has one linearly independent eigenvector and the eigenvalue 位鈧 = b has its own linearly independent eigenvector. Since the total number of linearly independent eigenvectors for the given matrix is 2, which is less than the size of the matrix (3), the given matrix is defective.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Let \(\lambda\) be an eigenvalue of an \(n \times n\) matrix \(A\) and let \(\mathbf{x}\) be an eigenvector belonging to \(\lambda .\) Show that \(e^{\lambda}\) is an eigenvalue of \(e^{A}\) and \(\mathbf{x}\) is an eigenvector of \(e^{A}\) belonging to \(e^{\lambda}\)

Let \(T\) be an upper triangular matrix with distinct diagonal entries (i.e., \(t_{i i} \neq t_{j j}\) whenever \(i \neq j\) ). Show that there is an upper triangular matrix \(R\) that diagonalizes \(T\)

It follows from Exercise 14 that, for a diagonalizable matrix, the number of nonzero eigenvalues (counted according to multiplicity) equals the rank of the matrix. Give an example of a defective matrix whose rank is not equal to the number of nonzero eigenvalues.

Let \(A\) be a singular \(n \times n\) matrix. Show that \(A^{T} A\) is positive semidefinite, but not positive definite.

The city of Mawtookit maintains a constant population of 300,000 people from year to year. A political science study estimated that there were 150,000 Independents, 90,000 Democrats, and 60,000 Republicans in the town. It was also estimated that each year 20 percent of the Independents become Democrats and 10 percent become Republicans. Similarly, 20 percent of the Democrats become Independents and 10 percent become Republicans, while 10 percent of the Republicans defect to the Democrats and 10 percent become Independents each year. Let \\[ \mathbf{x}=\left(\begin{array}{r} 150,000 \\ 90,000 \\ 60,000 \end{array}\right) \\] and let \(\mathbf{x}^{(1)}\) be a vector representing the number of people in each group after one year (a) Find a matrix \(A\) such that \(A \mathbf{x}=\mathbf{x}^{(1)}\) (b) Show that \(\lambda_{1}=1.0, \lambda_{2}=0.5,\) and \(\lambda_{3}=0.7\) are the eigenvalues of \(A,\) and factor \(A\) into a product \(X D X^{-1},\) where \(D\) is diagonal (c) Which group will dominate in the long run? Justify your answer by computing \(\lim _{n \rightarrow \infty} A^{n} \mathbf{x}\)

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.