Final answer:
The minimum value of a function is the lowest point on its graph. For the given function f(x), which is a horizontal line for 0 ≤ x ≤ 20, the minimum value is equal to the constant value of the function, which is 20.
Step-by-step explanation:
The minimum value of a function is the lowest point on its graph. In the given context, the function f(x) is a horizontal line for 0 ≤ x ≤ 20. Since the graph is a horizontal line and the value of y does not change within this interval, the minimum value is equal to the constant value of the function, which is the y-coordinate of any point on the line. So, the minimum value of the function f(x) is 20.