Question 7 • Precalculus
The inverse is f⁻¹(x) = −√(x − 4), so its input must satisfy x − 4 ≥ 0, or x ≥ 4. Because the inverse uses the negative square-root branch, the original function f(x) = x² + 4 must be restricted to inputs x ≤ 0. Therefore, the correct conclusion is that the domain of f is x ≤ 0 and the domain of f⁻¹ is x ≥ 4.
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