Definition 1 Minor of an element aij of a determinant is the determinant obtained by
deleting its ith row and jth column in which element aij lies Minor of an element aij is
denoted by Mij Remark Minor of an element of a determinant of order n(n ≥ 2) is a determinant of
order n – 1 Example 8 Find the minor of element 6 in the determinant 
1
2
3
4
5
6
7
8
9
∆ =
Solution Since 6 lies in the second row and third column, its minor M23 is given by
M23 =
1
2
7
8  = 8 – 14 = – 6 (obtained by deleting R2 and C3 in ∆)