MCQ
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 $x$.
- A$\pm 2$
- B$\pm 3$
- C$\pm 6$
- D$\pm 4$
✓
Answer
$
\begin{array}{l}
\text { (c) : }\left|\begin{array}{cc}
2 x & 5 \\
8 & x
\end{array}\right|=\left|\begin{array}{cc}
6 & -2 \\
7 & 3
\end{array}\right| \Rightarrow 2 x^2-40=18+14 \\
\Rightarrow x^2=36 \Rightarrow x= \pm 6
\end{array}
$
\begin{array}{l}
\text { (c) : }\left|\begin{array}{cc}
2 x & 5 \\
8 & x
\end{array}\right|=\left|\begin{array}{cc}
6 & -2 \\
7 & 3
\end{array}\right| \Rightarrow 2 x^2-40=18+14 \\
\Rightarrow x^2=36 \Rightarrow x= \pm 6
\end{array}
$
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