Given a square matrix, the cofactor of aij is denoted by Aij=(−1)i+jMij, where Mij is the minor of the entry aij
Mij=∣∣∣2564∣∣∣
From the matrix, a32=5
Determinant of A32=(−1)3+2∣∣∣2564∣∣∣=−(−8−30)=22
Therefore, a32.A32=5×22=110.
If Δ∣∣ ∣∣a11a12a13a21a22a23a31a32a33∣∣ ∣∣ and Aij is cofactor of aij, then value of Δ is given by
a) a11A31+a12A32+a13A33 b) a11A11+a12A21+a13A31 c) a21A11+a22A12+a23A13 d) a11A11+a21A21+a31A31