## College Algebra 7th Edition

$M= \left[ {\begin{array}{cc} 9 & -4 \\ -2 & 1 \\ \end{array} } \right]$
We use the the formula $M= \frac{1}{ad-bc} \left[ {\begin{array}{cc} d & -b \\ -c & a \\ \end{array} } \right]$ $M= \frac{1}{1} \left[ {\begin{array}{cc} 9 & -4 \\ -2 & 1 \\ \end{array} } \right]$