Final answer:
The difference quotient can be used to find both average and instantaneous rates of change; average rate over an interval, and instantaneous rate as that interval approaches zero.
Step-by-step explanation:
The difference quotient is indeed used to determine both average and instantaneous rates of change. For the average rate of change, you would use the difference quotient over an interval, which means taking the change in the function value, Δf, over the change in the independent variable, Δt, resulting in Δf/Δt. For instantaneous rate of change, the difference quotient is used as the interval approaches zero, which is essentially the derivative of the function at a point, and can be interpreted as the slope of the tangent line to the graph of the function at that point.