If $A=\left[\begin{array}{ccc}1 & 0 & 2 \ 2 & 1 & 3 \ 0 & 3 & -5\end{array} ight]$, where $A_{ ext {ij }}$ is the cofactor of the element $a_{ ext {ij }}$ of matrix $A$, then $a_{21} A_{21}+a_{22} A_{22}+a_{23} A_{23}=$

Question

If $A=\left[\begin{array}{ccc}1 & 0 & 2 \ 2 & 1 & 3 \ 0 & 3 & -5\end{array}ight]$, where $A_{	ext {ij }}$ is the cofactor of the element $a_{	ext {ij }}$ of matrix $A$, then $a_{21} A_{21}+a_{22} A_{22}+a_{23} A_{23}=$

Aicharya · Accepted Answer

$\begin{aligned} a_{21} & A_{21}+a_{22} A_{22}+a_{23} A_{23} \ &=-2(0-6)+1(-5-0)-3(3-0) \ &=12-5-9=-2 \end{aligned}$

If $A=\left[\begin{array}{ccc}1 & 0 & 2 \\ 2 & 1 & 3 \\ 0 & 3 & -5\end{array}\right]$, where $A_{\text {ij…

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