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Question
Find the value of x from the following : \[\begin{vmatrix}x & 4 \\ 2 & 2x\end{vmatrix} = 0\]
Solution
\[\begin{vmatrix}x & 4 \\ 2 & 2x\end{vmatrix} = 0\]
\[ \Rightarrow 2 x^2 - 8 = 0\]
\[ \Rightarrow 2 x^2 = 8\]
\[ \Rightarrow x^2 = \frac{8}{2} = 4\]
\[ \Rightarrow x = \sqrt{4} = \pm 2\]
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