Hello!
Answer:

Explanation:
→ We want to find the value of f(4).
→ We know that f(x) is equal to:

→ To find f(4), let's replace x by 4 in the function x:

→ Simplify:

Conclusion:
If the function x is equal to √(x-3), the image of 4 by the function x is equal to 1.