Question

$A=\left[\begin{array}{cc}1& 2\\ 2& 3\end{array}\right]$

$A^2=?$

Answer 1

$A=\left[\begin{array}{cc}1& 2\\ 2& 3\end{array}\right]$

$A^2=\left[\begin{array}{cc}1& 2\\ 2& 3\end{array}\right]$$\left[\begin{array}{cc}1& 2\\ 2& 3\end{array}\right]$

$A^2=\left[\begin{array}{cc}1+4& 2+6\\ 2+6& 4+9\end{array}\right]$

$A^2=\left[\begin{array}{cc}5& 8\\ 8& 13\end{array}\right]$