Practicing Success
Let A be a square matrix of order 3 such that $adj. (adj. (adj. A)) =\begin{bmatrix}16&0&-24\\0&4&0\\0&12&4\end{bmatrix}$. Then find $|A|$ |
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We know that $adj. (adj. A) = |A|^{n-2}A$, where n is order of matrix. $∴adj. (adj. (adj. A)) = |adj. A|^{n-2} adj. A$ $=(|A|^{n-2})^{(n-2)} adj. A$ For n = 3, $adj. (adj. (adj. A)) = |A|^2 adj. A =\begin{bmatrix}16&0&-24\\0&4&0\\0&12&4\end{bmatrix}$ $∴|A|^6|adj. A|=256$ $⇒|A|^6|A|^2=2^8$ $⇒|A|=2$ |