Elementary Linear Algebra 7th Edition

Published by Cengage Learning
ISBN 10: 1-13311-087-8
ISBN 13: 978-1-13311-087-3

Chapter 2 - Matrices - Review Exercises - Page 98: 12

Answer

$$A^T=\left[\begin{array}{rrr}{3} & {2} \\ {-1} & {0} \end{array}\right].$$ $$A^TA=\left[\begin{array}{rrr}{13} & {-3} \\ {-3} & {1} \end{array}\right].$$ $$AA^T=\left[\begin{array}{rrr}{10} & {6} \\ {6} & {4} \end{array}\right].$$

Work Step by Step

Let $A$ be given by $$A=\left[\begin{array}{rrr}{3} & {-1} \\ {2} & {0} \end{array}\right].$$ Now, we have $$A^T=\left[\begin{array}{rrr}{3} & {2} \\ {-1} & {0} \end{array}\right].$$ $$A^TA=\left[\begin{array}{rrr}{3} & {2} \\ {-1} & {0} \end{array}\right]\left[\begin{array}{rrr}{3} & {-1} \\ {2} & {0} \end{array}\right]=\left[\begin{array}{rrr}{13} & {-3} \\ {-3} & {1} \end{array}\right].$$ $$AA^T=\left[\begin{array}{rrr}{3} & {-1} \\ {2} & {0} \end{array}\right]\left[\begin{array}{rrr}{3} & {2} \\ {-1} & {0} \end{array}\right]=\left[\begin{array}{rrr}{10} & {6} \\ {6} & {4} \end{array}\right].$$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.