Chapter 3 Linear Systems and Matrices - 3.8 Use Inverse Matrices to Solve Linear Systems - Guided Practice for Example 1 - Page 210: 3

$A^{-1}=\begin{bmatrix} -1 &2\\ \frac{1}{2} & \frac{-3}{2} \end{bmatrix}$

$A^{-1}=\frac{1}{6-4}\begin{bmatrix} -2 &4\\ 1 & -3 \end{bmatrix}=\frac{1}{2}\begin{bmatrix} -2 &4\\ 1 & -3 \end{bmatrix}=\begin{bmatrix} -1 &2\\ \frac{1}{2} & \frac{-3}{2} \end{bmatrix}$