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Determinants — MATHS STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceMATHSDeterminants1 Mark
Question
If $\left|\begin{array}{cc}2 x & 5 \\ 8 & x\end{array}\right|=\left|\begin{array}{cc}6 & -2 \\ 7 & 3\end{array}\right|,$ then find the value of $x.$
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Answer

$ \begin{array}{l} \left|\begin{array}{cc} 2 x & 5 \\ 8 & x \end{array}\right|=\left|\begin{array}{cc} 6 & -2 \\ 7 & 3
\end{array}\right| \end{array}$
$\Rightarrow 2 x^2-40=18+14  $
$ \Rightarrow x^2=36 $
$\Rightarrow x= \pm 6 $

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