6. $$\mathbf { M } = \left( \begin{array} { l l } 2 & 3
0 & 1 \end{array} \right) .$$ Prove by induction that \(\mathbf { M } ^ { n } = \left( \begin{array} { c c } 2 ^ { n } & 3 \left( 2 ^ { n } - 1 \right)
0 & 1 \end{array} \right)\), for all positive integers \(n\).