If \Delta=\begin{vmatrix}a&b&c\\ d&e&f\\ g&h&i\end{vmatrix} and A, B, C, D, G are the cofactors of the elements a, b, c, d, g respectively, then what is bB+cC-dD-gG equal to?
- A. 0 ✓
- B. 1
- C. \Delta
- D. -\Delta
Correct Answer: A. 0
Explanation
Expanding by 1st row: aA + bB + cC = \Delta. Expanding by 1st column: aA + dD + gG = \Delta. Subtracting these equations gives bB + cC - dD - gG = 0.
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