logo

Ask Questions, Get Answers

 
X
 Search
Want to ask us a question? Click here
Browse Questions
Ad
Home  >>  CBSE XII  >>  Math  >>  Determinants
0 votes

Find the value of $x$, if $ \begin{vmatrix} 2&4 \\ 5&1 \end{vmatrix} = \begin{vmatrix} 2x&4 \\ 6&x \end{vmatrix}$

Can you answer this question?
 
 

1 Answer

0 votes
Toolbox:
  • A determinant of order $2\times 2$ can be evaluated as $\begin{vmatrix}a_{11} & a_{12}\\a_{21} & a_{22}\end{vmatrix}$
  • $\mid A\mid=a_{11}a_{22}-a_{21}a_{12}$
Find the values of x if
 
(i)$\begin{vmatrix}2 & 4\\5 & 1\end{vmatrix}=\begin{vmatrix}2x &4\\6 & x\end{vmatrix}$
 
We know the value of determinant of order $2\times 2$ is $(a_{11}a_{22}-a_{21}a_{12})$
 
Hence LHS=$2\times 1-5\times 4$
 
$\qquad\qquad=2-20$
 
$\qquad\qquad=-18$
 
RHS=$2x\times x-6\times 4$
 
$\qquad=2x^2-24$
 
Now equating the both,
 
$2x^2-24=-18$
 
$\Rightarrow 2x^2=24-18$
 
$\;\;2x^2=6$
 
$\Rightarrow x^2=\frac{6}{2}=3$
 
$x=\pm\sqrt 3$.

 

answered Feb 20, 2013 by sreemathi.v
edited Feb 20, 2013 by sreemathi.v
 

Related questions

Ask Question
student study plans
x
JEE MAIN, CBSE, NEET Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App
...