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: 19

Answer

$\begin{bmatrix} 15&21&-16\\ 22&34&-22\\ -11&7&22 \end{bmatrix}$

Work Step by Step

To Find: $C(A+B)$ $\textbf {I}: A+B$ $\begin{bmatrix} 0&3&-5\\ 1&2&6 \end{bmatrix}+\begin{bmatrix} 4&1&0\\ -2&3&-2 \end{bmatrix}$: Let the resultant be matrix M. We add two matrices by adding the respective individual elements of each matrix. $\implies M = \begin{bmatrix} 4&4&-5\\ -1&5&4 \end{bmatrix}$ $\textbf{II}: CM$ $\begin{bmatrix} 4&1\\ 6&2\\ -2&3 \end{bmatrix}\times\begin{bmatrix} 4&4&-5\\ -1&5&4 \end{bmatrix}$ Let the resultant matrix be $Z$. $\implies Z_{1,1} = (4)(4)+(1)(-1) = 15$ $\implies Z_{1,2} = (4)(4)+(1)(5) = 21$ $\implies Z_{1,3} = (4)(-5)+(1)(4) = -16$ $\implies Z_{2,1} = (6)(4)+(2)(-1) = 22$ $\implies Z_{2,2} = (6)(4)+(2)(5) = 34$ $\implies Z_{2,3} = (6)(-5)+(2)(4) = -22$ $\implies Z_{3,1} = (-2)(4)+(3)(-1) = -11$ $\implies Z_{3,2} = (-2)(4)+(3)(5) = 7$ $\implies Z_{3,3} = (-2)(-5)+(3)(4) = 22$ $\therefore Z = \begin{bmatrix} 15&21&-16\\ 22&34&-22\\ -11&7&22 \end{bmatrix}$
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