3 and 4 .Determinants and Matrices
easy

જો $\left|\begin{array}{cc}x & 2 \\ 18 & x\end{array}\right|=\left|\begin{array}{cc}6 & 2 \\ 18 & 6\end{array}\right|$ હોય, તો $x =$ ........... .

A

$6$

B

$ \pm 6$

C

$-6$

D

$0$

Solution

$\left|\begin{array}{ll}x & 2 \\ 18 & x\end{array}\right|=\left|\begin{array}{ll}6 & 2 \\ 18 & 6\end{array}\right|$

$\Rightarrow x^{2}-36=36-36$

$\Rightarrow x^{2}-36=0$

$\Rightarrow x^{2}=36$

$\Rightarrow x=\pm 6$

Hence, the correct answer is $\mathrm{B}$.

Standard 12
Mathematics

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