The function f: [0, ∞) → [0, ∞) defined by f(x) = x² is:

The function f: [0, ∞) → [0, ∞) defined by f(x) = x² is:

• A. One-one but not onto
• B. Onto but not one-one
• C. Bijective
• D. Neither one-one nor onto

Answer: C) Bijective

Explanation: On non-negative reals, x₁² = x₂² strictly implies x₁ = x₂, making it one-one. Every non-negative real y has a non-negative real square root √y, making it onto. Thus, it's bijective.