HSC Arts 12th Board ExamMaharashtra State Board
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If A^-1=1/3[[1,4,-2],[-2,-5,4],[1,-2,1]]` and | A | = 3, then (adj. A) = - HSC Arts 12th Board Exam - Mathematics and Statistics

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Question

If `A^-1=1/3[[1,4,-2],[-2,-5,4],[1,-2,1]]` and | A | = 3, then (adj. A) = _______

(A)`1/9[[1,4,-2],[-2,-5,4],[1,-2,1]]`

(B)`[[1,-2,1],[4,-5,-2],[-2,4,1]]`

(C)`[[1,4,-2],[-2,-5,4],[1,-2,1]]`

(D)`[[-1,-4,2],[2,5,-4],[1,-2,1]]`

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]]`

 

 

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APPEARS IN

 2014-2015 (October) (with solutions)
Question 1.1.2 | 2.00 marks

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