Derivative Checker

Jan Mays
Observe the slope at A, a point on f(x). Let D be a point whose x-value is the same as point A and whose y-value is f '(x). Slide A and observe what happens to point D
Describe the behavior of D. Why does D begin below the x-axis? What can you say about f(x) when D is on the x-axis? Why does this make sense?