If $A = \begin{bmatrix}2 & 1 \\ 0 & 3\end{bmatrix}$, what is $A^2$?

Explanation

1. 01

   $A^2$ means $AA$, a matrix product, row by column.

2. 02

   Row 1, column 2: $2(1) + 1(3) = 5$; the other elements are $4$, $0$ and $9$.

3. 03

   So $A^2 = \begin{bmatrix}4 & 5 \\ 0 & 9\end{bmatrix}$.