# Derivative Checker

- Author:
- Jan Mays

- Topic:
- Derivative

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?

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