Search any question & find its solution
Question:
Answered & Verified by Expert
If $P=\left[\begin{array}{lll}1 & \alpha & 3 \\ 1 & 3 & 3 \\ 2 & 4 & 4\end{array}\right]$ is the adjoint of a $3 \times 3$ matrix A and $|A|=4$, then value of $\alpha$ is
Options:
Solution:
1739 Upvotes
Verified Answer
The correct answer is:
$11$
$\begin{aligned} & P=\operatorname{adj} A \\ \therefore \quad & |\mathrm{P}|=|\mathrm{A}|^2 \\ & \Rightarrow\left|\begin{array}{lll}1 & \alpha & 3 \\ 1 & 3 & 3 \\ 2 & 4 & 4\end{array}\right|=4^2 \\ & \Rightarrow 2 \alpha-6=16 \\ & \Rightarrow \alpha=11\end{aligned}$
Looking for more such questions to practice?
Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.