$\begin{array}{1 1} M_{12} = b, M_{21} = c, M_{22} = a \quad A_{11} = d, A_{12} = -b, A_{21} = -c, A_{22} = a \\ M_{12} = b, M_{21} = c, M_{22} = a \quad A_{11} = c, A_{12} = -c, A_{21} = -c, A_{22} = a \\ M_{12} = b, M_{21} = c, M_{22} =a \quad A_{11} = d, A_{12} = -c, A_{21} = -b, A_{22} = a \\ M_{12} = a, M_{21} = c, M_{22} = b \quad A_{11} = d, A_{12} = -b, A_{21} = -c, A_{22} = a \end{array} $