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The minors of -4 and 9 and the co-factors of -4 and 9 in determinant $\left|\begin{array}{ccc}-1 & -2 & 3 \\ -4 & -5 & -6 \\ -7 & 8 & 9\end{array}\right|$ are respectively
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The correct answer is:
$-42,-3 ; 42,-3$
Minor of $-4=\left|\begin{array}{cc}-2 & 3 \\ 8 & 9\end{array}\right|=-42,\left|\begin{array}{ll}-1 & -2 \\ -4 & -5\end{array}\right|=-3$
and cofactor of $-4=(-1)^{2+1}(-42)=42$,
cofactor of $9=(-1)^{3+3}(-3)=-3$.
and cofactor of $-4=(-1)^{2+1}(-42)=42$,
cofactor of $9=(-1)^{3+3}(-3)=-3$.
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