Algebra 2 Common Core

Published by Prentice Hall
ISBN 10: 0133186024
ISBN 13: 978-0-13318-602-4

Chapter 12 - Matrices - 12-2 Matrix Multiplication - Practice and Problem-Solving Exercises - Page 777: 12

Answer

$3A+2B=\begin{bmatrix} 3 & 14 \\ 22 & -14 \\ 1 & 10 \end{bmatrix} $

Work Step by Step

Multiplying each element of $A= \begin{bmatrix} 3 & 4 \\ 6 & -2 \\ 1 & 0 \end{bmatrix} $ by $3,$ and then adding the result to $2$ times each element of $B= \begin{bmatrix} -3 & 1 \\ 2 & -4 \\ -1 & 5 \end{bmatrix} ,$ then \begin{align*} 3A+2B&= \begin{bmatrix} 3(3) & 4(3) \\ 6(3) & -2(3) \\ 1(3) & 0(3) \end{bmatrix} + \begin{bmatrix} -3(2) & 1(2) \\ 2(2) & -4(2) \\ -1(2) & 5(2) \end{bmatrix} \\\\&= \begin{bmatrix} 9 & 12 \\ 18 & -6 \\ 3 & 0 \end{bmatrix} + \begin{bmatrix} -6 & 2 \\ 4 & -8 \\ -2 & 10 \end{bmatrix} \\\\&= \begin{bmatrix} 9+(-6) & 12+2 \\ 18+4 & -6+(-8) \\ 3+(-2) & 0+10 \end{bmatrix} \\\\&= \begin{bmatrix} 9-6 & 12+2 \\ 18+4 & -6-8 \\ 3-2 & 0+10 \end{bmatrix} \\\\&= \begin{bmatrix} 3 & 14 \\ 22 & -14 \\ 1 & 10 \end{bmatrix} .\end{align*} Hence, $ 3A+2B=\begin{bmatrix} 3 & 14 \\ 22 & -14 \\ 1 & 10 \end{bmatrix} .$
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