Exam Strategy
Calculus BC · AP · Contextual Applications of Differentiation
CED focus
Rates of Change in Applied Contexts Other Than Motion
This topic is assessed on the AP Exam.
Multiple-choice tips
- Identify whether the stem tests a definition, rule, or application.
- Identify the independent variable (often time) in related-rates MC.
- Eliminate L’Hospital uses when the limit is not indeterminate.
- Check linearization: is the estimate over or under?
- Match units on related-rates distractors.
Free-response tips
- Label f′(a) meaning in context; show the rule that justifies each step.
- Draw and label a related-rates diagram before differentiating.
- Show dV/dt (or similar) setup with correct chain rule.
- State L’Hospital hypotheses before applying.
- For linearization, show f(a) + f′(a)(x − a) with a labeled tangent point.
Common traps
- Mixing average rate over an interval with instantaneous rate at a point
- Plugging values before differentiating in related rates
- Using L’Hospital on a non-indeterminate form
- Linearizing at the wrong point a
Quick checklist
- [ ] Can set up a related-rates equation with labels
- [ ] Can state when L’Hospital applies
- [ ] Can write a local linearization formula