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3 and 4 .Determinants and Matrices
medium
$\alpha$ के मानों की संख्या, जिसके लिये समीकरण निकाय:
$x+y+z=\alpha$
$\alpha x+2 \alpha y+3 z=-1$
$x+3 \alpha y+5 z=4$ असंगत है, होंगी
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