Question

What is the domain and range of `F(x)=sqrtx`?

Answer 1

It depends. The domain is in a sense user-defined.

Explanation:

Whoever who created this function chooses his own domain.

For example, if I made this function, I could define its domain to be `[4,9]`. In that case, the corresponding range would be `[2,3]`.

But what I think you are asking for is the largest possible domain of `F`. Any domain of `F` must be a subset of the largest possible domain.

The largest possible domain for `F` is `[0,oo)`.
The corresponding range is `[0,oo)`.