if A is a square matrix of order 3 such that modulus A = 5 then write the value of A (adj A)

In the given question, we are given a square matrix of order 3 such that A=5. We need to find A.adjA.

Here, use the formula A-1=adjAA. So,
A-1.A=adjA

Next, multiply left hand side and right hand side by A, we get
A.A-1.A=A.adjA

No, use the fact that A.A-1=I3 where I3 is the identity matrix of order 3. So,
A.I3=A.adjAA.I3=A.adjAA3=A.adjA53=A.adjAA.adjA=125

Therefore, A.adjA=125

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25

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