3 and 4 .Determinants and Matrices
easy

Find values of ${x},$ if  $\left|\begin{array}{ll}2 & 3 \\ 4 & 5\end{array}\right|=\left|\begin{array}{ll}x & 3 \\ 2 x & 5\end{array}\right|$

A

$x=2$

B

$x=3$

C

$x=4$

D

$x=5$

Solution

$\left|\begin{array}{ll}2 & 3 \\ 4 & 5\end{array}\right|=\left|\begin{array}{ll}x & 3 \\ 2 x & 5\end{array}\right|$

$\Rightarrow 2 \times 5-3 \times 4=x \times 5-3 \times 2 x$

$\Rightarrow 10-12=5 x-6 x$

$\Rightarrow-2=-x$

$\Rightarrow x=2$

Standard 12
Mathematics

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