If x & y 4 & 2 =7 and 2 & 3 y & x =4 then, - Vidyadip

MCQ

If $ \begin{vmatrix}\text{x} &\text{amp; y}\\ 4 &\text{amp; } 2 \end{vmatrix}=7$ and $ \begin{vmatrix}2 &\text{amp; }3\\ \text{y} &\text{amp; } \text{x} \end{vmatrix}=4$ then,

A
$\text{x}=-3, \text{ y}=-\dfrac {5}{2}$
✓
$\text{x}=-\dfrac {5}{2}, \text{y}=-3$
C
$\text{x}=-3, \text{ y}=\dfrac {5}{2}$
D
$\text{x}=-\dfrac {5}{2}, \text{ y}=3$

✓

Answer

Correct option: B.

$\text{x}=-\dfrac {5}{2}, \text{y}=-3$

$ \begin{vmatrix}\text{x} &\text{amp; y}\\ 4 &\text{amp; } 2 \end{vmatrix}=7$
$\Rightarrow2\text{x}-4\text{y}=7$
$ \begin{vmatrix}2 &\text{amp; }3\\ \text{y} &\text{amp; } \text{x} \end{vmatrix}=4$
$\Rightarrow2\text{x}-3\text{y}=4$
$\therefore\text{x}=-\dfrac {5}{2}, \text{y}=-3$

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