Answer:
The function f(x) = x represents a straight line with a slope of 1, passing through the origin (0,0).
If we consider the interval from x = 2 to x = 9, we can see that the line starts at f(2) = 2 and ends at f(9) = 9.
Therefore, over the interval from x=2 to x=9, the function f(x) = x increases in a straight line fashion from 2 to 9.
In other words, the slope of the line is positive, and the function is monotonically increasing on this interval.