COMEDK · Maths · 22. Determinants
The cofactor of the element \(a_{21}\) in the expansion of \(\Delta=\left|\begin{array}{ccc}1 & 4 & 4 \\ -3 & 5 & 9 \\ 2 & 1 & 2\end{array}\right|\) is
- A \(-4\)
- B \(-5\)
- C \(-24\)
- D 5
Answer & Solution
Correct Answer
(A) \(-4\)
Step-by-step Solution
Detailed explanation
The element \(a_{21}\) is the element in the second row and first column of the determinant \(\Delta = \begin{vmatrix} 1 & 4 & 4 \\ -3 & 5 & 9 \\ 2 & 1 & 2 \end{vmatrix}\). The value of \(a_{21}\) is \(-3\). The cofactor \(C_{ij}\) of an element \(a_{ij}\) is given by…
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