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3 and 4 .Determinants and Matrices
medium
$x$ के मान ज्ञात कीजिए यदि
$\left|\begin{array}{ll}2 & 4 \\ 5 & 1\end{array}\right|=\left|\begin{array}{cc}2 x & 4 \\ 6 & x\end{array}\right|$
A
$ x=\pm \sqrt{2}$
B
$ x=\pm \sqrt{7}$
C
$ x=\pm \sqrt{6}$
D
$ x=\pm \sqrt{3}$
Solution
$\left|\begin{array}{ll}2 & 4 \\ 5 & 1\end{array}\right|=\left|\begin{array}{cc}2 x & 4 \\ 6 & x\end{array}\right|$
$\Rightarrow 2 \times 1-5 \times 4=2 x \times x-6 \times 4$
$\Rightarrow 2-20=2 x^{2}-24$
$\Rightarrow 2 x^{2}=6$
$\Rightarrow x^{2}=3$
$\Rightarrow x=\pm \sqrt{3}$
Standard 12
Mathematics
