The square root function f(x) = √x is defined only for non-negative values of x. In this case, if the domain is specified as x ≥ 7, it means that we are only looking at values of x starting from 7 and going upwards. Therefore, the square root of any value in this domain will also be non-negative.
Given this domain condition, the statement that must be true is: The function f(x) will always return a real number, specifically a non-negative number, for any input x in the domain x ≥ 7.
For example, if we substitute x with 7, we have f(7) = √7, which is a positive real number. If we substitute x with 8, we get f(8) = √8, which again is a positive real number. This holds true for any x that is greater than or equal to 7.