10. ADJOINT OF A SQUARE MATRIX :
Let A= [aij] =
be a square matrix and let the matrix formed by
the cofactors of [aij] in determinant is
(adj A ) =
Hence the transpose of the matrix of cofactors of elements of A in det. A is called the adj A.
Note: If
Hence adjoint of a square matrix of order 2 can be easily obtained by interchanging the diagonal elements and changing the signs of the off fiagonal elements.
Example
