16. If matrix $\mathrm{A}=\left[\begin{array}{cc}2& -3\\ 3& 4\end{array}\right]$, then show that A^{2} – 6A + 17I = 0 and hence find A^{–1}.
17. If matrix $\mathrm{A}=\left[\begin{array}{cc}2& 3\\ 1& 2\end{array}\right]$, then show that A^{2} – 4A + I = 0 and hence find A^{–1}.