Write Minors and Cofactors of the elements of following determinants:
Minor of an element aij = Mij �
a11 = 1, Minor of element a11 = M11 = = (1 × 1) – (0 × 0) = 1
Here removing 1st row and 1st column from the determinant we are left out with the determinant. Solving this we get M11 = 1
Similarly, finding other Minors of the determinant
a12 = 0, Minor of element a12 = M12 = = (0 × 1) – (0 × 0) = 0
a13 = 0, Minor of element a13 = M13 = = (0 × 0) - (1 × 0) = 0
a21 = 0, Minor of element a21 = M21 = = (0 × 1) – (0 × 0) = 0
a22 = 1, Minor of element a22 = M22 = = (1 × 1) – (0 × 0) = 1
a23 = 0, Minor of element a23 = M23 = = (1 × 0) – (0 × 0) = 0
a31 = 0, Minor of element a31 = M31 = = (0 × 0) – (0 × 1) = 0
a32 = 0, Minor of element a32 = M32 = = (1 × 0) – (0 × 0) = 0
a33 = 1, Minor of element a33 = M33 = = (1 × 1) – (0 × 0) = 1
Cofactor of an element aij, Aij = (-1)i+j × Mij
A11 = (-1)1+1 × M11 = 1 × 1 = 1
A12 = (-1)1+2 × M12 = (-1) × 0 = 0
A13 = (-1)1+3 × M13 = 1 × 0 = 0
A21 = (-1)2+1 × M21 = (-1) × 0 = 0
A22 = (-1)2+2 × M22 = 1 × 1 = 1
A23 = (-1)2+3 × M23 = (-1) × 0 = 0
A31 = (-1)3+1 × M31 = 1 × 0 = 0
A32 = (-1)3+2 × M32 = (-1) × 0 = 0
A33 = (-1)3+3 × M33 = 1 × 1 = 1