If A be a square matrix of order 3 , such that A = 5 , then A d j - 3 A - 2 is equal to

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Question: Answered & Verified by Expert

If

A

be a square matrix of order

3

, such that

|A| = \sqrt{5}

, then

|A d j (- 3 A^{- 2})|

is equal to

MathematicsDeterminantsJEE Main

Solution:

2643 Upvotes Verified Answer

The correct answer is: 29.16

|A d j (- 3 A^{2})| = {|(- 3 A^{- 2})|}^{2} = 3^{6} {|A^{- 2}|}^{2} = 3^{6} \times \frac{1}{{|A|}^{4}}

= 3^{6} \times \frac{1}{25} = \frac{729}{25} = 29.16

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