Question

The rank of the matrix $\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& 1& 0\\ 0& 0& 0& 1\end{array}\right)$ Is

• A. $2$
• B. $3$
• C. $4$
• D. None of these

Answer 1

The correct option is C $4$

Given,$\left[\begin{array}{cccc}1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& 1& 0\\ 0& 0& 0& 1\end{array}\right]$

It is an identity matrix of order $4.$

Hence, the rank of $A=4$