1 The matrix \(\mathbf { A }\) is given by \(\mathbf { A } = \left( \begin{array} { l l } a & 1
1 & 4 \end{array} \right)\), where \(a \neq \frac { 1 } { 4 }\), and \(\mathbf { I }\) denotes the \(2 \times 2\) identity matrix. Find
- \(2 \mathbf { A } - 3 \mathbf { I }\),
- \(\mathrm { A } ^ { - 1 }\).