Definition 1: Minor of an element aij of a determinant is the determinant obtained by deleting its rn row and fcolumn in which element aij lies. Minor of an element is denoted by Mij.
Note: Minor of an element of a determinant of order (n > 2) is a determinant of order n - 1.
Definition 2 : Cofactor of an element aij, denoted by is defined by Aij is defined by
Aij = (-1)i+j; Mij, where is minor of aij
Note: If elements of a row (or column) are multiplied with cofactors of any other row (or column), then their sum is zero. For example,
Similarly, we can try for other rows and columns.
