Exams › JEE Main › Maths
For a 3x3 determinant Δ with rows (a1, b1, c1), (a2, b2, c2), (a3, b3, c3), let A2, B2, C2 be the cofactors of a2, b2, c2 respectively. What is the value of a1*A2 + b1*B2 + c1*C2?
- -Δ
- 0
- Δ
- none of these
Correct answer: 0
Solution
Pairing row-1 elements with row-2 cofactors is equivalent to a determinant whose first and second rows are identical, which equals zero.
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