Linear Algebra and Its Applications (5th Edition)

Published by Pearson
ISBN 10: 032198238X
ISBN 13: 978-0-32198-238-4

Chapter 2 - Matrix Algebra - 2.1 Exercises - Page 102: 11

Answer

When A is right multiplied by D, its columns are multiplied by the diagonal entries of D. When A is left multiplied by D, its rows are multiplied by the diagonal entries of D. B can be any scalar multiple of A or any power of A.

Work Step by Step

A=$\begin{bmatrix} 1 & 1 & 1 \\ 1 & 2 & 3\\ 1 & 4 & 5\\ \end{bmatrix} $ and D=$\begin{bmatrix} 2 & 0 & 0 \\ 0 & 3 & 0\\ 0 & 0 & 5\\ \end{bmatrix} $ AD=$\begin{bmatrix} 2 & 3 & 5\\ 2 & 6 & 15\\ 2 & 12 & 25\\ \end{bmatrix} $ When A is right multiplied by D, its columns are multiplied by the diagonal entries of D. DA=$\begin{bmatrix} 2 & 2 & 2\\ 3 & 6 & 9\\ 5 & 20 & 25\\ \end{bmatrix} $ When A is left multiplied by D, its rows are multiplied by the diagonal entries of D. B can be any scalar multiple of A or any power of A. If $B=A^2=\begin{bmatrix} 3 & 7 & 9\\ 6 & 17 & 22\\ 10 & 29 & 38\\ \end{bmatrix} $ $AB=\begin{bmatrix} 19 & 53 & 69\\ 45 & 128 & 167\\ 77 & 220 & 287\\ \end{bmatrix} $ and $BA=\begin{bmatrix} 19 & 53 & 69\\ 45 & 128 & 167\\ 77 & 220 & 287\\ \end{bmatrix} $
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