Answer:
The range is [-1, ∞).
Explanation:
The points where the graph of this function cut the x axis are at x = 2 and x = 4 , it opens upwards and has a minimum value.
It has a minimum value when x = (2 + 4) / 2 = 3.
When x = 3, f(x) = (3 - 4)(3 - 2) = -1.
So the range is all real values of x >= -1, or [-1, ∞)