Answer
The three matrices are $I=\left[\begin{array}{cc}
1&0\\
0&1
\end{array}\right]$ and $O=\left[\begin{array}{cc}
0&0\\
0&0
\end{array}\right]$ and the matrix $\left[\begin{array}{cc}
1&0\\
0&0
\end{array}\right]$
Work Step by Step
The three matrices are $I=\left[\begin{array}{cc}
1&0\\
0&1
\end{array}\right]$ and $O=\left[\begin{array}{cc}
0&0\\
0&0
\end{array}\right]$ and the matrix $\left[\begin{array}{cc}
1&0\\
0&0
\end{array}\right]$
because $I^{2}=I$ and $O^{2}=O$ and
$\left[\begin{array}{cc}
1&0\\
0&0
\end{array}\right]$ $\left[\begin{array}{cc}
1&0\\
0&0
\end{array}\right]$=$\left[\begin{array}{cc}
1&0\\
0&0
\end{array}\right]$
