The co-factors of the elements of second column of $\left[\begin{array}{ccc}1 & -1 & 2 \ 3 & 2 & 1 \ -1 & 3 & 4\end{array} ight]$ are

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The co-factors of the elements of second column of $\left[\begin{array}{ccc}1 & -1 & 2 \ 3 & 2 & 1 \ -1 & 3 & 4\end{array}ight]$ are

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Required cofactors are as follows: $\begin{aligned} & \mathrm{A}_{12}=(-1)^{1+2}\left|\begin{array}{cc} 3 & 1 \ -1 & 4 \end{array}ight|=-(12+1)=-13 \ & \mathrm{~A}_{22}=(-1)^{2+2}\left|\begin{array}{cc} 1 & 2 \ -1 & 4 \end{array}ight|=(4+2)=6 \ & \mathrm{~A}_{32}=(-1)^{3+2}\left|\begin{array}{cc} 1 & 2 \ 3 & 1 \end{array}ight|=-(-1-6)=5 \end{aligned}$

The co-factors of the elements of second column of $\left[\begin{array}{ccc}1 & -1 & 2 \\ 3 & 2 & 1 \\ -1 &…

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