Question

The scalar matrix is

• A. $\left[\begin{array}{cc}-1& 3\\ 2& 4\end{array}\right]$
• B. $\left[\begin{array}{cc}0& 3\\ 2& 0\end{array}\right]$
• C. $\left[\begin{array}{cc}4& 0\\ 0& 4\end{array}\right]$
• D. None of these

Answer 1

Answer: (C)

$\left[\begin{array}{cc}4& 0\\ 0& 4\end{array}\right]$

A diagonal matrix with all its main diagonal entries equal is a scalar matrix, that is, a scalar multiple of the identity matrix
Therefore, $\left[\begin{array}{cc}4& 0\\ 0& 4\end{array}\right]$ is a scalar matrix.
$\therefore$ Ans: C