Chapter 9 Quadratic Relations and Conic Sections - 9.3 Graph and Write Equations of Circles - 9.3 Exercises - Mixed Review - Page 632: 77

$$\begin{pmatrix}-53&-13\\ 40&9\\ 53&24\end{pmatrix}$$

Multiplying the two matrices using the rules of matrices, we find: $$\begin{pmatrix}2\left(-4\right)+\left(-5\right)\cdot \:9+0\cdot \:7&2\cdot \:1+\left(-5\right)\cdot \:3+0\cdot \:4\\ 1\cdot \left(-4\right)+8\cdot \:9+\left(-4\right)\cdot \:7&1\cdot \:1+8\cdot \:3+\left(-4\right)\cdot \:4\\ 2\left(-4\right)+6\cdot \:9+1\cdot \:7&2\cdot \:1+6\cdot \:3+1\cdot \:4\end{pmatrix} \\ \begin{pmatrix}-53&-13\\ 40&9\\ 53&24\end{pmatrix}$$