If $\left|\begin{array}{cc}x & 2 \\ 18 & x\end{array}\right|=\left|\begin{array}{cc}6 & 2 \\ 18 & 6\end{array}\right|,$ then $x$ is equal to
If $\left|\begin{array}{cc}x & 2 \\ 18 & x\end{array}\right|=\left|\begin{array}{cc}6 & 2 \\ 18 & 6\end{array}\right|,$ then $x$ is equal to
$\left|\begin{array}{ll}x & 2 \\ 18 & x\end{array}\right|=\left|\begin{array}{ll}6 & 2 \\ 18 & 6\end{array}\right|$
$\Rightarrow x^{2}-36=36-36$
$\Rightarrow x^{2}-36=0$
$\Rightarrow x^{2}=36$
$\Rightarrow x=\pm 6$
Hence, the correct answer is $\mathrm{B}$.
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