Practice Test 4

Let $A=\begin{pmatrix}1&0\2&-1\end{pmatrix}$ and $O=\begin{pmatrix}0&0\0&0\end{pmatrix}$. What is the result of $AO$?

For $A=\begin{pmatrix}2&-1\0&3\end{pmatrix}$ and $I=\begin{pmatrix}1&0\0&1\end{pmatrix}$, what is the result of $AI$?