i) Showing all of your working, compute the matrix inverse of the matrix \left(\begin{array}{ccc}

2 & 7 & -2 \\

2 & 0 & -2 \\

9 & -2 & 4

\end{array}\right) ) Hence, or otherwise, find the value of a such that the matrix \left(\begin{array}{ccc}

a & 3 & -7 \\

2 & 0 & -2 \\

9 & -2 & 4

\end{array}\right) O Using Cramer's rule, solve the system of simultaneous equations x + 2yz = 3, x+y+z = 1, -2x+y=3z = 4. Solving by any other method will not score any marks.