A–1 = \(\begin{bmatrix}3&-1&1\\-15&6&-5\\5&-2&2\end{bmatrix}\)and B = \(\begin{bmatrix}1&2&-2\\-1&3&0\\0&-2&1\end{bmatrix}\)
|B| = 1(3 – 0) – 2( – 1 – 0) – 2(2 – 0)
= 3 + 2 – 4
|B| = 1
Now, B–1 = \(\frac{1}{|B|}adjB\)
Cofactors of B are:
C11 = – 3 C21 = 2 C31 = 6
C12 = 1 C22 = 1 C32 = 2
C13 = 2 C23 = 2 C33 = 5