If , prove that A – 1 = AT.
A = AT =
|A| = [ – 8(16 + 56) – 1(16 – 7) + 4( – 32 – 4)]
= – 81
Cofactors of A are:
C11 = 72 C21 = – 36 C31 = – 9
C12 = – 9 C22 = – 36 C32 = 72
C13 = – 36 C23 = – 63 C33 = – 36
adj A =
=
So, adj A =
Now, A – 1 =
Hence, A – 1 = = AT