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Determinants — Applied Maths STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceApplied MathsDeterminants2 Marks
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

$\left|\begin{array}{cc}2 x & 5 \\ 8 & x\end{array}\right|=\left|\begin{array}{cc}6 & -2 \\ 7 & 3\end{array}\right|$
$2 x^2-40=18+14$
$\text{or } 2 x^2=32+40$
$\text{or }2 x^2=72$
$\text{or }x^2=36$
$\text{or}\quad x= \pm 6$

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