দেওয়া আছে, A=\left[\[\begin{array}{ll}4 & 2 \\ 3 & 5\end{array}\]\right]
\therefore \mathrm{A}^2=\mathrm{A} . \mathrm{A}=\left[\[\begin{array}{ll} 4 & 2 \\ 3 & 5 \end{array}\]\right]\left[\[\begin{array}{ll} 4 & 2 \\ 3 & 5 \end{array}\]\right]
=\left[\[\begin{array}{cc} 16+6 & 8+10 \\ 12+15 & 6+25 \end{array}\]\right]=\left[\[\begin{array}{ll} 22 & 18 \\ 27 & 31 \end{array}\]\right]
\therefore \mathrm{A}^2-5 \mathrm{~A}+6 \mathrm{I}=\left[\[\begin{array}{ll} 22 & 18 \\ 27 & 31 \end{array}\]\right]-5\left[\[\begin{array}{ll} 4 & 2 \\ 3 & 5 \end{array}\]\right]+6\left[\[\begin{array}{ll} 1 & 0 \\ 0 & 1 \end{array}\]\right]
=\left[\[\begin{array}{ll} 22 & 18 \\ 27 & 31 \end{array}\]\right]-\left[\[\begin{array}{ll} 20 & 10 \\ 15 & 25 \end{array}\]\right]+\left[\[\begin{array}{ll} 6 & 0 \\ 0 & 6 \end{array}\]\right]
=\left[\[\begin{array}{ll} 22-20+6 & 18-10+0 \\ 27-15+0 & 31-25+6 \end{array}\]\right]
=\left[\[\begin{array}{cc} 8 & 8 \\ 12 & 12 \end{array}\]\right] \text{ (Ans.) }