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 - 2.2 Properties of Matrix Operations - 2.2 Exercises - Page 60: 39

Answer

$(AB)^T=B^TA^T$.

Work Step by Step

Since we have $$AB=\left[\begin{array}{ccc}{-1} &{1} & {-2} \\{2} & {0}& {1} \end{array}\right]\left[\begin{array}{cc}{-3} &{0} \\{1}& {2} \\{1} &{-1} \end{array}\right]=\left[\begin{array}{cc}{2} &{4} \\{-5}& {-1} \end{array}\right]$$ then $$(AB)^T=\left[\begin{array}{cc}{2} &{-5} \\{4}& {-1} \end{array}\right].$$ Now, $$B^TA^T=\left[\begin{array}{ccc}{-3} &{1}&{1} \\{0}& {2} &{-1} \end{array}\right]\left[\begin{array}{ccc}{-1} &{2} \\{1} & {0} \\ {-2}&{1} \end{array}\right] =\left[\begin{array}{cc}{2} &{-5} \\{4}& {-1} \end{array}\right].$$ It is easy to see that $(AB)^T=B^TA^T$.
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.