Question:
The matrix $A=\left[\begin{array}{lll}0 & 0 & 4 \\ 0 & 4 & 0 \\ 4 & 0 & 0\end{array}\right]$ is a
(a) square matrix
(b) diagonal matrix
(c) unit matrix
(d) none of these
Solution:
Given: $A=\left[\begin{array}{lll}0 & 0 & 4 \\ 0 & 4 & 0 \\ 4 & 0 & 0\end{array}\right]$
Since, number of rows is equal to number of columns.
Therefore, A is a square matrix.
Hence, the correct option is (a).