$A=\left[\begin{array}{ll}1 & 2 \\ 2 & 1\end{array} ight]$ and $B=\left[\begin{array}{ll}x & y \\ 1 & 2\end{array} ight]$ are two matrices such that $(A+B)(A-B)=A^{2}-B^{2}$ If $C=\left[\begin{array}{ll}x & 2 \\ 1 & y\end{array} ight]$, then trace $(C)=$

Question

$A=\left[\begin{array}{ll}1 & 2 \\ 2 & 1\end{array}ight]$ and $B=\left[\begin{array}{ll}x & y \\ 1 & 2\end{array}ight]$ are two matrices such that $(A+B)(A-B)=A^{2}-B^{2}$ If $C=\left[\begin{array}{ll}x & 2 \\ 1 & y\end{array}ight]$, then trace $(C)=$

Accepted Answer

Correct answer: A

More Matrices And Determinants questions