Question:
If $A=\left(\begin{array}{ccc}3 & 4 & 1 \\ 1 & 0 & -2 \\ -2 & -1 & 2\end{array}\right)$ then $A^{-1}=?$
A. $\left(\begin{array}{ccc}2 & 9 & -8 \\ -2 & 8 & 7 \\ -1 & 5 & -4\end{array}\right)$
B. $\left(\begin{array}{ccc}-2 & 9 & -8 \\ 2 & 8 & 7 \\ -1 & -5 & 4\end{array}\right)$
c. $\left(\begin{array}{ccc}-2 & -9 & -8 \\ 2 & 8 & 7 \\ -1 & -5 & -4\end{array}\right)$
D. None of these
Solution:
$\left(\begin{array}{ccc}-2 & -9 & -8 \\ 2 & 8 & 7 \\ -1 & -5 & -4\end{array}\right)$