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
Answer & explanation
Correct answer: option 3
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.