Question

What is the domain and range of `f(x) = sqrt(x - 8)`?

Answer 1

The domain is given setting the argument bigger or equal to zero to avoid a negative square root:
`x-8>=0`
So the domain is all the real `x` bigger or equal to `8`.
The range must be all the `y` bigger or equal to `0` because your square root cannot devolve a negative value.

Graphically:
graph{sqrt(x-8) [-0.45, 50.86, -4.48, 21.2]}