If , find (AT) – 1.
A =
Let B = AT =
|B| =
= ( – 1 – 8) – 0 – 2( – 8 + 3) = – 9 + 10 = 1
Cofactors of B are:
C11 = – 9 C21 = 8 C31 = – 5
C12 = – 8 C22 = 7 C32 = – 4
C13 = – 2 C23 = 2 C33 = – 1
adj B =
=
So, adj B =
Now, B – 1 =
Hence, (AT) – 1