Having troubles showing A has no inverse or finding the inverse, matrices.

mr_coffee

Hello everyone, this problem is dealing with Finite Feilds with matrices. I got the answers from the book and i'm trying to understand what they did to get the answers...
For the first one it says, Find 1/a in Fp.
a = 17 in F_37

Then the other one says:
In each case either show that A h as no iverse or find A^-1.

Here is my work:
http://show.imagehosting.us/show/758..._-1_758469.jpg