3 and 4 .Determinants and Matrices
medium

સમીકરણ સહતિ  $x+y+z=\alpha$  ; $\alpha x+2 \alpha y+3 z=-1$  ;   $x+3 \alpha y+5 z=4$    સુસંગત થાય તેવી $\alpha$ ની કિંમતોની સંખ્યા ............ છે.

A

$0$

B

$1$

C

$2$

D

$3$

(JEE MAIN-2022)

Solution

$x+y+z=\alpha$

$\alpha x+2 \alpha y+3 z=-1$

$x+3 \alpha y+5 z=4$

Has inconsistent solution

$D =\left|\begin{array}{ccc}1 & 1 & 1 \\ \alpha & 2 \alpha & 3 \\ 1 & 3 \alpha & 5\end{array}\right|=0$

$\Rightarrow(\alpha-1)^{2}=0$

$\alpha=1$

For $\alpha=1$

$D_{1}=\left|\begin{array}{ccc}1 & 1 & 1 \\ -1 & 2 & 3 \\ 4 & 3 & 5\end{array}\right|$

$=(10-9)-(-5-12)+(-3-8)$

$=1+17-11 \neq 0$

For $\alpha=1$ the system of equation has Inconsistent solution

Standard 12
Mathematics

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