Assuming that the domain of the given function is the set of all real numbers R, so that the variable x takes all values in the interval
(−∞,+∞)
If x takes all values in the interval (−∞,+∞) then 4 x + 5 takes all values in the interval (−∞,+∞) and the range of the given function is given by the interval (−∞,+∞)