This AP Calculus AB exam reference sheet summarizes the core ideas students use most often during review: limits, continuity, derivatives, applications of derivatives, integrals, and accumulation. It is designed to help students quickly connect definitions, rules, and common problem types. A strong reference sheet is useful because AP questions often mix several skills in one problem.
Keeping the main formulas in one place supports faster recall and more accurate work.
Key Facts
- The limit definition of the derivative is when the limit exists.
- A function is continuous at if is defined, exists, and .
- The product rule is .
- The quotient rule is , where .
- The chain rule is .
- Critical numbers occur where or is undefined, as long as is in the domain of .
- The net change theorem says .
- The Fundamental Theorem of Calculus says if , then when is continuous.
Vocabulary
- Limit
- A limit describes the value a function approaches as the input approaches a particular number.
- Continuity
- Continuity at means the graph has no break there and satisfies .
- Derivative
- A derivative gives the instantaneous rate of change of a function and the slope of its tangent line.
- Critical Number
- A critical number is a domain value where or where does not exist.
- Definite Integral
- A definite integral represents signed area and accumulated change over an interval.
- Accumulation Function
- An accumulation function has the form and measures total change from to .
Common Mistakes to Avoid
- Forgetting to check continuity before using the Intermediate Value Theorem is wrong because the theorem only applies when the function is continuous on .
- Using as the only test for extrema is wrong because extrema can also occur where is undefined or at endpoints of a closed interval.
- Dropping the inner derivative in the chain rule is wrong because must include the factor .
- Treating as total area every time is wrong because the definite integral gives signed area, so regions below the -axis count as negative.
- Confusing position, velocity, and acceleration is wrong because if is position, then and .
Practice Questions
- 1 Find .
- 2 Differentiate .
- 3 Evaluate .
- 4 Explain why a function can have a local maximum at a point where does not exist.
Understanding AP Calc AB Exam Reference Sheet
Limits are the language for describing behavior near a point, even when a function has a hole, jump, or vertical asymptote there. A graph can show the idea quickly, but it can hide important details. Students should compare values approaching from the left with values approaching from the right.
If those approaches disagree, there is no two-sided limit. A limit can exist even when the function has no value at that input.
This distinction matters when deciding whether a discontinuity can be repaired by defining one missing value. On exam problems, read tables carefully because values very close to an input matter more than the value exactly at that input.
A derivative connects a changing quantity to its instantaneous rate of change. Its meaning depends on context. For position, the derivative is velocity.
For velocity, the derivative is acceleration. For a volume of water, the derivative tells how fast the volume changes per unit of time. Units are one of the best error checks available.
If a position is measured in meters and time in seconds, velocity must be in meters per second. Derivative rules save time, but students need to recognize the structure before choosing a rule. A product has two changing factors.
A quotient has a changing denominator. A nested expression has an outside function acting on an inside function. Missing the inside rate is a common chain rule error.
Derivative applications focus on behavior rather than just calculation. A positive derivative means the function rises as the input increases. A negative derivative means it falls.
The second derivative describes how the slope itself changes. It helps identify concavity, which affects the shape of a graph and the meaning of local extrema. Critical numbers are only starting points.
They do not automatically prove a maximum or minimum. Students must test nearby behavior, use sign changes, or compare function values on a closed interval.
Real problems often add domain limits, such as time beginning at zero or a physical length that cannot be negative. Ignoring those limits can produce an answer that is mathematically possible but physically meaningless.
Integrals accumulate many small contributions. A definite integral measures signed accumulation, so regions below the horizontal axis contribute negatively. This is why an integral is not always the same as geometric area.
To find total area, separate portions above and below the axis before combining their positive sizes. Accumulation functions appear in problems about distance traveled, fluid entering a tank, medication entering the bloodstream, and money earned over time. Their graphs deserve careful attention.
The value of an accumulation function can increase even when the original rate is decreasing, as long as the rate remains positive. On free response work, state what a result means in context and include units.
On calculator problems, distinguish a numerical estimate from an exact expression. Clear interpretation earns credit even when arithmetic is imperfect.