Question

Find the minors and cofactors of all the elements of the following determinant.

`|(5,20),(0, -1)|`

Answer 1

`|(5,20),(0, -1)|`

Minor of 5 = M₁₁ = -1
Minor of 20 = M₁₂ = 0
Minor of 0 = M₂₁ = 20
Minor of -1 = M₂₂ = 5
Cofactor of 5 = A₁₁ = (-1)¹⁺¹ M₁₁ = 1 × -1 = -1
Cofactor of 20 = A₁₂ = (-1)¹⁺² M₁₂ = -1 × 0 = 0
Cofactor of 0 = A₂₁ = (-1)²⁺¹ M₂₁ = -1 × 20 = -20
Cofactor of -1 = A₂₂ = (-1)²⁺² M₂₂ = 1 × 5 = 5