1.

If A =\(\begin{vmatrix}α&2\\2&α\end{vmatrix}\)and |A3 | = 125, then α = ___________A = [(α, 2) (2, α)](a) ±3 (b) ±2 (c) ±5 (d) 0

Answer»

Correct option is : (a) ±3

|A3 | = 125 

|A|3 = 53 …….[∵ |An | = |A|n , n ∈ N] 

∴ |A| = 5 

\(\begin{vmatrix}α&2\\2&α\end{vmatrix}\)=5

α2 – 4 = 5 

α2 = 9 

∴ α = ± 3



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