Q3 of 74 Page 7

For the matrix A= , show that A(adj A)=O.

A =


Cofactors of A


C11 = 30 C21 = 12 C31 = – 3


C12 = – 20 C22 = – 8 C32 = 2


C13 = – 50 C23 = – 2 0 C33 = 5


adj A =


=


So, adj(A) =


Now, A.(adj A) =


=


=


Hence, A(adj A) = 0


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