1.
$$\mathbf { M } = \left( \begin{array} { c c }
2 k + 1 & k
k + 7 & k + 4
\end{array} \right) \quad \text { where } k \text { is a constant }$$
- Show that \(\mathbf { M }\) is non-singular for all real values of \(k\).
- Determine \(\mathbf { M } ^ { - 1 }\) in terms of \(k\).