3 and 4 .Determinants and Matrices
hard

ધારો કે સદીશો $x_{1}, x_{2}$ અને $x_{3}$ એ સુરેખ સમીકરણ સંહિતાના ઉકેલો હોય તથા $Ax = b$ જ્યાં સદીશ $b$ અનુક્રમે $b _{1}, b _{2}$ અને $b _{3}$ આપેલ છે જો $x =\left[\begin{array}{l}1 \\ 1 \\ 1\end{array}\right], x _{2}=\left[\begin{array}{l}0 \\ 2 \\ 1\end{array}\right], x _{3}=\left[\begin{array}{l}0 \\ 0 \\ 1\end{array}\right], b _{1}=\left[\begin{array}{l}1 \\ 0 \\ 0\end{array}\right]$ $b _{2}=\left[\begin{array}{l}0 \\ 2 \\ 0\end{array}\right]$ and $b _{3}=\left[\begin{array}{l}0 \\ 0 \\ 2\end{array}\right],$ હોય તો $A$ નો નિશ્ચયાક શોધો 

A

$\frac{1}{2}$

B

$4$

C

$\frac{3}{2}$

D

$2 $

(JEE MAIN-2020)

Solution

$A x_{1}=b_{1}$

$A x_{2}=b_{2}$

$A x_{3}=b_{3}$

$\Rightarrow\left|\begin{array}{lll}1 & 0 & 0 \\ 1 & 2 & 0 \\ 1 & 1 & 1\end{array}\right|=\left|\begin{array}{lll}1 & 0 & 0 \\ 0 & 2 & 0 \\ 0 & 0 & 2\end{array}\right|$

$\Rightarrow|A|=\frac{4}{2}=2$

Standard 12
Mathematics

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