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Home  >>  JEEMAIN and AIPMT  >>  Mathematics  >>  Class12  >>  Determinants
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If the system of equations $x+2y-3z=1$, $(p+2)z=3$, $(2p+1)y+z=2$ is inconsistent, then the value of $p$ is

$(a)\;-2\qquad(b)\;1\qquad(c)\;0\qquad(d)\;2$

Can you answer this question?
 
 

1 Answer

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The augmented matrix is C=[A B]
$\Rightarrow \begin{vmatrix}1&2&-3&1\\0&0&p+2&3\\0&2p+1&1&2\end{vmatrix}$
$R_2\leftrightarrow R_3$
$\Rightarrow \begin{vmatrix}1&2&-3&1\\0&2p+1&1&2\\0&0&p+2&3\end{vmatrix}$
The system of equations is inconsistent if $r(A)=2$ and $r(C)=3$
Now,$r(A)=2$ if $p+2=0$
(i.e) $p=-2$
Hence (a) is the correct answer.
answered Nov 26, 2013 by sreemathi.v
 

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