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Let A = [a ij ] 2 × 2 , where a ij ≠ 0 for all i, j and A 2 = I. Let a be the sum of all diagonal elements of A and b = |A|. Then 3a 2 + 4b 2 is equal to-

1. 4
2. 14
3. 7
4. 3T

Correct answer: 4

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