Final answer:
The function rule in slope-intercept form for the given graph is f(x) = 3x + 9.
Step-by-step explanation:
The function rule in slope-intercept form, f(x) = mx + b, represents a linear function on a coordinate plane. The slope-intercept form is y = mx + b, where m is the slope of the line and b is the y-intercept.
From the given information, we know that the y-intercept is 9 and the slope is 3. Therefore, the function rule in slope-intercept form for the given graph is f(x) = 3x + 9.
This means that for every unit increase in x, there is a corresponding increase of 3 units in y, and the line intersects the y-axis at the point (0, 9).