**how to find the inverse**

The inverse can be found by setting this matrix equal to the identity matrix and row reducing so that the identity matrix is on the other side of equal sign (the inverse matrix will be where the identity matrix is originally).

So

1 2 -3 | 1 0 0

3 2 -1 | 0 1 0

2 1 3 | 0 0 1

Does that help?