We know the square of a real number is never negative.

Clearly, f(x) takes real values only when x² – 16 ≥ 0

⇒ x² – 4² ≥ 0

⇒ (x + 4)(x – 4) ≥ 0

⇒ x ≤ –4 or x ≥ 4

∴ x ∈ (–∞, –4] ∪ [4, ∞)

Thus, domain of f = (–∞, –4] ∪ [4, ∞)

When x ∈ (–∞, –4] ∪ [4, ∞), we have x² – 16 ≥ 0

Hence,

∴ f(x) ∈ [0, ∞)

Thus, range of f = [0, ∞)