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$\pm 3$
- ✓$\pm 6$
- D$\pm 4$
✓
Answer
Correct option: C.
$\pm 6$
$\left|\begin{array}{cc} 2 x & 5 \\ 8 & x \end{array}\right|=\left|\begin{array}{cc} 6 & -2 \\ 7 & 3
\end{array}\right|$
$ \Rightarrow 2 x^2-40=18+14$
$\Rightarrow x^2=36$
$ \Rightarrow x= \pm 6$
\end{array}\right|$
$ \Rightarrow 2 x^2-40=18+14$
$\Rightarrow x^2=36$
$ \Rightarrow x= \pm 6$
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