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Let A be a non-singular symmetric matrix of order 3 . If A T = A 2 - I , then A - I - 1 is equal to

Options

  1. AA
  2. B2 A
  3. CA - I
  4. D2 A - I

Correct answer

A. A

Step-by-step solution

∵ A T = A (as A is symmetric) ∴ A = A 2 - I ⇒ A 2 - A = I ⇒ I = A A - I = A - I A ⇒ A - I - 1 = A

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