Hello all, i need some help with domain and ranges of composite functions.

1.) f: R --> R, f(x) = X^2 - 4

g: R+ union {0} ----> R, g(x) = sqrt(x)

The question was to find f(g(x)) which i found to be x-4. The other part of the question was to find the range which i was completely lost on. Please HELP!

Thanks in advance.