Answer
\[
M=
\left[ {\begin{array}{cc}
2/3 & 4/3 & 3\\
1 & 1 & 3 \\
1/3 & 2/3 & 1 \\
\end{array} } \right]
\]
Work Step by Step
We plug this into a graphing calculator as stated into the calculator. It is important to remember the calculator will find the inverse by solving for a second matrix, and thus the answer will be a decimal on most calculator. If using a TI calculator, pushing $\triangle frac$ will put the answer into fractions.
After doing above we get...
\[
M=
\left[ {\begin{array}{cc}
2/3 & 4/3 & 3\\
1 & 1 & 3 \\
1/3 & 2/3 & 1 \\
\end{array} } \right]
\]
