A square matrix $B =[a_{ij}]_{n×n}$ is called a unit matrix if :
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → $a_{ij}=\left\{\begin{matrix}1; & i=j\\0; & i≠j\end{matrix}\right.$
A unit matrix is,
$a_{ij}=\left\{\begin{matrix}1; & i=j\\0; & i≠j\end{matrix}\right.$ → Diagonal element