Question

In the above question, a₁₁ C₂₁ + a₁₂ C₂₂ + a₁₃ C₂₃ = __________.

Answer 1

Given:
|A| = 5

As we know,
Sum of products of elements of row (or column) with their corresponding cofactors = Value of the determinant
and
Sum of products of elements of row (or column) with the cofactors of any other row (or column) = 0


Thus, a₁₁ C₂₁ + a₁₂ C₂₂ + a₁₃ C₂₃ = 0

Hence, a₁₁ C₂₁ + a₁₂ C₂₂ + a₁₃ C₂₃ = 0.