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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 f(a)=limh0f(a+h)f(a)hf'(a)=\lim_{h\to 0}\frac{f(a+h)-f(a)}{h} when the limit exists.
  • A function is continuous at x=ax=a if f(a)f(a) is defined, limxaf(x)\lim_{x\to a}f(x) exists, and limxaf(x)=f(a)\lim_{x\to a}f(x)=f(a).
  • The product rule is ddx[u(x)v(x)]=u(x)v(x)+u(x)v(x)\frac{d}{dx}[u(x)v(x)]=u'(x)v(x)+u(x)v'(x).
  • The quotient rule is ddx[u(x)v(x)]=v(x)u(x)u(x)v(x)[v(x)]2\frac{d}{dx}\left[\frac{u(x)}{v(x)}\right]=\frac{v(x)u'(x)-u(x)v'(x)}{[v(x)]^2}, where v(x)0v(x)\ne 0.
  • The chain rule is ddxf(g(x))=f(g(x))g(x)\frac{d}{dx}f(g(x))=f'(g(x))g'(x).
  • Critical numbers occur where f(x)=0f'(x)=0 or f(x)f'(x) is undefined, as long as xx is in the domain of ff.
  • The net change theorem says abf(x)dx=f(b)f(a)\int_a^b f'(x)\,dx=f(b)-f(a).
  • The Fundamental Theorem of Calculus says if F(x)=axf(t)dtF(x)=\int_a^x f(t)\,dt, then F(x)=f(x)F'(x)=f(x) when ff is continuous.

Vocabulary

Limit
A limit describes the value a function approaches as the input approaches a particular number.
Continuity
Continuity at x=ax=a means the graph has no break there and satisfies limxaf(x)=f(a)\lim_{x\to a}f(x)=f(a).
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 f(x)=0f'(x)=0 or where f(x)f'(x) does not exist.
Definite Integral
A definite integral abf(x)dx\int_a^b f(x)\,dx represents signed area and accumulated change over an interval.
Accumulation Function
An accumulation function has the form F(x)=axf(t)dtF(x)=\int_a^x f(t)\,dt and measures total change from aa to xx.

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 [a,b][a,b].
  • Using f(x)=0f'(x)=0 as the only test for extrema is wrong because extrema can also occur where f(x)f'(x) is undefined or at endpoints of a closed interval.
  • Dropping the inner derivative in the chain rule is wrong because ddxf(g(x))\frac{d}{dx}f(g(x)) must include the factor g(x)g'(x).
  • Treating abf(x)dx\int_a^b f(x)\,dx as total area every time is wrong because the definite integral gives signed area, so regions below the xx-axis count as negative.
  • Confusing position, velocity, and acceleration is wrong because if s(t)s(t) is position, then v(t)=s(t)v(t)=s'(t) and a(t)=v(t)=s(t)a(t)=v'(t)=s''(t).

Practice Questions

  1. 1 Find limx2x24x2\lim_{x\to 2}\frac{x^2-4}{x-2}.
  2. 2 Differentiate y=(3x21)5y=(3x^2-1)^5.
  3. 3 Evaluate 03(2x+1)dx\int_0^3 (2x+1)\,dx.
  4. 4 Explain why a function can have a local maximum at a point where f(x)f'(x) does not exist.