1. The problem is to understand if you need to find the derivative every time to calculate the rate of change. 2. The rate of change of a function at a point is given by the derivative of the function at that point. 3. The derivative of a function $f(x)$ is defined as $$f'(x) = \lim_{h \to 0} \frac{f(x+h) - f(x)}{h}$$ which represents the instantaneous rate of change. 4. For average rate of change over an interval $[a,b]$, you use $$\frac{f(b) - f(a)}{b - a}$$ which does not require the derivative. 5. So, if you want the instantaneous rate of change at a specific point, you must find the derivative. 6. If you want the average rate of change over an interval, you do not need the derivative, just the function values at the endpoints. 7. In summary, finding the derivative is necessary for instantaneous rate of change but not always for rate of change in general.