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KCET2008MathematicsMatrices

If A ( adj A )=5 I where I is the identity matrix of order 3 , then adj A is equal to

Options

  1. A125
  2. B25
  3. C5
  4. D10

Correct answer

B. 25

Step-by-step solution

Given, A( adj A)=5 I aligned & | A | I =5 I | A |=5 & | adj ( A )|=| A |³⁻¹=| A |²=(5)²=25 aligned

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