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

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