## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$\begin{bmatrix} {9}&{2}\\ {34}&{13}\\ {47}&{20}\end{bmatrix}$
Since $A$ is a $3 \times 3$ matrix and $B$ is a $3 \times 2$ matrix, the product $AB$ is defined as a $3 \times 2$ matrix. $$AB=\begin{bmatrix} {(1)(1)+(0)(6)+(1)(8)}&{(1)(3)+0(2)+1(-1)}\\ {(2)(1)+(4)(6)+(1)(8)}&{(2)(3)+(4)(2)+(1)(-1)}\\ {(3)(1)+(6)(6)+(1)(8)}&{(3)(3)+(6)(2)+(1)(-1)}\end{bmatrix} \\=\begin{bmatrix} {1+0+8}&{3+0+(-1)}\\ {2+24+8}&{6+8+(-1)}\\ {3+36+8}&{9+12+(-1)}\end{bmatrix} \\=\begin{bmatrix} {9}&{2}\\ {34}&{13}\\ {47}&{20}\end{bmatrix}$$