JEE Mains · Maths · STD 12 - 3 and 4 . metrices and determinant
If \(P = \left[ {\begin{array}{*{20}{c}}1&\alpha &3\\1&3&3\\2&4&4\end{array}} \right]\) is the adjoint of \(3×3 \) matrix \(A\) and \( |A|=4\) then \(\alpha \) is equal to
- A \(4\)
- B \(11\)
- C \(5\)
- D \(0\)
Answer & Solution
Correct Answer
(B) \(11\)
Step-by-step Solution
Detailed explanation
\(|P|=1(12-12)-\alpha(4-6)+3(4-6)\) \(=2 \alpha-6\) \(|P|=|A|^{2}=16\) \(2 \alpha-6=16\) \(\alpha=11.\)
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