Question

Select the correct option from the given alternatives:

If A = `[(alpha, 2),(2, alpha)]` and |A³| = 125, then α = _______

Options

• ±3

• ±2

• ±5

• 0

Answer 1

If A = `[(alpha, 2),(2, alpha)]` and |A³| = 125, then α = ±3

Explanation:

|A| = α² – 4 

∴ |A|³ = (α² – 4)³ = 125 = (5)³

∴ α² –  4 = 5

∴ α² = 9

∴ α = ±3