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If A is invertible 2 × 2 and A² = I then A is
Aa zero matrix (typical)
Balways identity
Cskew-symmetric
Da self-inverse matrix (A = A^{-1})
Answer & Solution
Correct answer: D. a self-inverse matrix (A = A^{-1})
1. A² = I means A·A = I, so A acts as its own inverse.
2. Equivalently A = A^{-1}.
3. Such matrices are called involutory.
_Source: Maharashtra Balbharati Std XII Mathematics Part 1, Ch 2 "Matrices" §2.6_
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