6.
$$\mathbf { A } = \left( \begin{array} { r r }
2 & 1
- 1 & 0
\end{array} \right) \text { and } \mathbf { B } = \left( \begin{array} { r r }
- 1 & 1
0 & 1
\end{array} \right)$$
Given that \(\mathbf { M } = ( \mathbf { A } + \mathbf { B } ) ( 2 \mathbf { A } - \mathbf { B } )\),
- calculate the matrix \(\mathbf { M }\),
- find the matrix \(\mathbf { C }\) such that \(\mathbf { M C } = \mathbf { A }\).