Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 9 - Systems and Matrices - 9.7 Properties of Matrices - 9.7 Exercises - Page 930: 45

Answer

\[\left[ {\begin{array}{*{20}{c}} {14}&{ - 2} \\ { - 12}&6 \end{array}} \right]\]

Work Step by Step

\[\begin{gathered} {\text{Let }}A = \left[ {\begin{array}{*{20}{c}} { - 2}&4 \\ 0&3 \end{array}} \right]{\text{ and }}B = \left[ {\begin{array}{*{20}{c}} { - 6}&2 \\ 4&0 \end{array}} \right] \hfill \\ {\text{Find }}2A - 3B \hfill \\ 2A - 3B = 2\left[ {\begin{array}{*{20}{c}} { - 2}&4 \\ 0&3 \end{array}} \right] - 3\left[ {\begin{array}{*{20}{c}} { - 6}&2 \\ 4&0 \end{array}} \right] \hfill \\ {\text{Use the scalar multiplication}} \hfill \\ 2A - 3B = \left[ {\begin{array}{*{20}{c}} { - 4}&8 \\ 0&6 \end{array}} \right] + \left[ {\begin{array}{*{20}{c}} {18}&{ - 6} \\ { - 12}&0 \end{array}} \right] \hfill \\ {\text{Add the corresponding elements}} \hfill \\ 2A - 3B = \left[ {\begin{array}{*{20}{c}} { - 4 + 18}&{8 - 6} \\ {0 - 12}&{6 - 0} \end{array}} \right] \hfill \\ {\text{Simplify}} \hfill \\ 2A - 3B = \left[ {\begin{array}{*{20}{c}} {14}&{ - 2} \\ { - 12}&6 \end{array}} \right] \hfill \\ \end{gathered} \]
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