If the trace of the matrix: $A=\left[\begin{array}{cccc}x-1 & 0 & 2 & 5 \\ 3 & x^2-2 & 4 & 1 \\ -1 & -2 & x-3 & 1 \\ 2 & 0 & 4 & x^2-6\end{array}\right]$ is 0 then $x$ is equal to

{–2, 3} (–2, 3) {–3, 2} (–3, 2)

{–3, 2}

Trace of matrix is defined as $\sum\limits_{i=1}^n a_{i i}=2 x^2+2 x-12=0$ ⇒ x = –3, 2 Hence (3) is the correct answer.