The diagonal entries of any skew-symmetric matrix are:
- Always $1$
- Always $0$
- Equal to each other but not necessarily $0$
- Always negative
Show answer and solution
Correct answer: B. Always $0$
A skew-symmetric matrix satisfies $a_{ij} = -a_{ji}$ for all $i, j$.
Setting $i = j$ gives $a_{ii} = -a_{ii}$, hence $2a_{ii} = 0$, so $a_{ii} = 0$.
Every diagonal entry of a skew-symmetric matrix is therefore zero.