Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Chapter 11 - Systems of Equations and Inequalities - 11.4 Matrix Algebra - 11.4 Assess Your Understanding - Page 758: 20

Answer

$\begin{bmatrix} 50&-3\\ 18&21 \end{bmatrix}$

Work Step by Step

To Find: (A+B)C $\textbf{I}: A+B$ We add two matrices by adding their respective individual elements. $\begin{bmatrix} 0&3&-5\\ 1&2&6 \end{bmatrix}+\begin{bmatrix} 4&1&0\\ -2&3&-2 \end{bmatrix} = \begin{bmatrix} 4&4&-5\\ -1&5&4 \end{bmatrix} = M$ $\textbf{II}: MC$ $\begin{bmatrix} 4&4&-5\\ -1&5&4 \end{bmatrix}\times\begin{bmatrix} 4&1\\ 6&2\\ -2&3 \end{bmatrix}$ Let the resultant matrix be $Z$. $\implies Z_{1,1} = (4)(4)+(4)(6)+(-5)(-2) = 50$ $\implies Z_{1,2} = (4)(1)+(4)(2)+(-5)(3) = -3$ $\implies Z_{2,1} = (-1)(4)+(5)(6)+(4)(-2) = 18$ $\implies Z_{2,2} = (-1)(1)+(5)(2)+(4)(3) = 21$ $\therefore Z = \begin{bmatrix} 50&-3\\ 18&21 \end{bmatrix}$
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