To determine the domain of the function represented by the line on the graph, we look at the x-values for which the function is defined.
Given that the line starts at the point (0, 9) and ends at the point (8, 1), the x-values range from 0 to 8. Therefore, the domain of the function is the interval of x-values between these two points.
In interval notation, the domain is:
\[ [0, 8] \]
This means the function is defined for all x-values from 0 to 8, inclusive.