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If

then ‘a’ is equal to :

 

  • Option 1)

    12

  • Option 2)

    24

  • Option 3)

    -12

  • Option 4)

    -24

 

Answers (2)

As we learnt in 

Value of determinants of order 3 -

-

 

 \begin{vmatrix} x^{2}+x & x+1 & x-2\\ 2x^{2}+3x-1 & 3x & 3x-3\\ x^{2}+2x+3& 2x-1 & 2x-1 \end{vmatrix} =ax-12

R_{2}\rightarrow R_{2}-\left ( R_{1}+R_{3} \right )

\begin{vmatrix} x^{2}+x & x+1 & x-2\\ -4 & 0 & 0\\ x^{2}+2x+3 & 2x-1 & 2x-1 \end{vmatrix}

\Rightarrow 4\left ( 6x-3 \right )=ax-12

\therefore 24x-12=ax-12

\Rightarrow a=24


Option 1)

12

This option is incorrect.

Option 2)

24

This option is correct.

Option 3)

-12

This option is incorrect.

Option 4)

-24

This option is incorrect.

Posted by

Sabhrant Ambastha

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