\(\mathbf{A} = \begin{pmatrix} k & -2 \\ 1-k & k \end{pmatrix}\), where \(k\) is a constant.
- Show that the matrix \(\mathbf{A}\) is non-singular for all values of \(k\). [2]
A transformation \(T : \mathbb{R}^2 \to \mathbb{R}^2\) is represented by the matrix \(\mathbf{A}\).
The point \(P\) has position vector \(\begin{pmatrix} a \\ 2a \end{pmatrix}\) relative to an origin \(O\).
The point \(Q\) has position vector \(\begin{pmatrix} 7 \\ -3 \end{pmatrix}\) relative to \(O\).
Given that the point \(P\) is mapped onto the point \(Q\) under \(T\),
- determine the value of \(a\) and the value of \(k\). [3]
Given that, for a different value of \(k\), \(T\) maps the line \(y = 2x\) onto itself,
- determine this value of \(k\). [3]