To find the domain of the function \( f(x) = \sqrt{x - 4} \), we need to determine for which values of \( x \) the expression inside the square root is non-negative, since the square root function is only defined for non-negative arguments.
Set up the inequality:
\[ x - 4 \geq 0 \]
Solving for \( x \):
\[ x \geq 4 \]
This means that \( x \) must be greater than or equal to 4. Therefore, the domain of the function \( f(x) \) in interval notation is:
\[ [4, \infty) \]
None of your provided responses exactly match this answer. However, the proper notation for the domain of \( f(x) \) with the included endpoint (4) is:
Answer: \([4, \infty)\)