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Determinants — MATHS STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceMATHSDeterminants1 Mark
Question
If $\left|\begin{array}{cc}3 x & 7 \\ -2 & 4\end{array}\right|=\left|\begin{array}{ll}8 & 7 \\ 6 & 4\end{array}\right|$ then find the value of $x$.
✓

Answer

$
\begin{aligned}
& & \left|\begin{array}{ll}
3 x & 7 \\
-2 & 4
\end{array}\right| & =\left|\begin{array}{ll}
8 & 7 \\
6 & 4
\end{array}\right| \\
\Rightarrow & & 12 x+14 & =32-42 \\
\Rightarrow & & 12 x & =-24 \\
\Rightarrow & & x & =-2
\end{aligned}
$

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