How do you find the domain and range of #y=2sqrtx#?
The domain of a function is the complete set of possible values of the independent variable.
The range of a function is the spread of possible y-values (minimum y-value to maximum y-value).
In this case if we stick with ONLY rational numbers, the x cannot be negative. Otherwise, we could have an infinite domain and range. With that constraint on x, the resulting range for y is also from zero to infinity.