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Let `A` be a square matrix of order 3 such that adj. (adj. (adj. A)) `=[(16,0,-24),(0,4,0),(0,12,4)]`. Then find (i) `|A|` (ii) adj. A |
Answer» 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-1))^((n-2))` adj. A For `n=3`, adj. (adj. (adj. A))`=|A|^(2)` adj. `A=[(16,0,-24),(0,4,0),(0,12,4)]` `:. |A|^(6)|"adj. A"|=256` `implies |A|^(6)|A|^(2)=2^(8)` `implies |A|=2` `implies` adj. `A=1/4 [(16,0,-24),(0,4,0),(0,12,4)]=[(4,0,-6),(0,1,0),(0,3,1)]` |
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