AIEEE 2003

JEE Main 2003 Mathematics question on Matrices and Determinants

If A=[α011]A = \begin{bmatrix} \alpha & 0 \\ 1 & 1 \end{bmatrix} and B=[1051]B = \begin{bmatrix} 1 & 0 \\ 5 & 1 \end{bmatrix} then value of α\alpha for which A2=BA^2 = B, is
  1. A.
    1
  2. B.
    -1
  3. C.
    4
  4. D.
    no real values
Show answer and solution

Correct option: D

Solution

Computing A² directly: A² = [[α², 0], [α+1, 1]]. Setting A² = B gives α² = 1 and α+1 = 5. From α² = 1, α = ±1, but α+1 = 5 requires α = 4. These two conditions are contradictory, so no real value of α satisfies both simultaneously.

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