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MCQ
If `A^-1=1/3[[1,4,-2],[-2,-5,4],[1,-2,1]]` and | A | = 3, then (adj. A) = _______
Options
`1/9[[1,4,-2],[-2,-5,4],[1,-2,1]]`
`[[1,-2,1],[4,-5,-2],[-2,4,1]]`
`[[1,4,-2],[-2,-5,4],[1,-2,1]]`
`[[-1,-4,2],[2,5,-4],[1,-2,1]]`
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Solution
(C)
`A^-1=1/|A|(adjA)`
`1/3[[1,4,-2],[-2,-5,4],[1,-2,1]]=1/3(adjA)`
`(adjA)=[[1,4,-2],[-2,-5,4],[1,-2,1]]`
Concept: Determinants - Adjoint Method
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