Step-by-step explanation:
[tex]A^2= \begin{bmatrix} 4 & 0 \\ 4 & 4 \end{bmatrix}[/tex]
Equate this to $hA + kI$
Thus,
[tex] A^2= h \begin{bmatrix} 2 & 0 \\ 1 & 2 \end{bmatrix} + k \begin{bmatrix} 1 & 0 \\ 0 & 1 \end{bmatrix}[/tex]
Hence we have the following equations (by equating corresponding terms on both sides):
$2h+k=4$
$h=4$
Solve these to get $h=4$ and $k=-4$
