JEE AdvancedHardQuestion 250017
Question
If A² = A (idempotent), then the eigenvalues of A are:
- A0 or 1Correct
- B1 or −1
- C0 or −1
- DOnly 1
Correct answer
0 or 1
Explanation
If λ is an eigenvalue of A with eigenvector v: Av = λv → A²v = λ²v. But A² = A → Av = λv → λ²v = λv → λ(λ−1)v = 0. Since v ≠ 0: λ = 0 or λ = 1.