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3 and 4 .Determinants and Matrices
easy
નિશ્ચાયકની કિમત મેળવો : $\left|\begin{array}{ccc}2 & -1 & -2 \\ 0 & 2 & -1 \\ 3 & -5 & 0\end{array}\right|$
A
$3$
B
$5$
C
$6$
D
$10$
Solution
Let $A=\left[\begin{array}{ccc}2 & -1 & -2 \\ 0 & 2 & -1 \\ 3 & -5 & 0\end{array}\right]$
By expanding along the first column, we have:
$|A|=2\left|\begin{array}{cc}2 & -1 \\ -5 & 0\end{array}\right|-0\left|\begin{array}{cc}-1 & -2 \\ -5 & 0\end{array}\right|+3\left|\begin{array}{cc}-1 & -2 \\ 2 & -1\end{array}\right|$
$=2(0-5)-0+3(1+4)$
$=-10+15=5$
Standard 12
Mathematics