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This AP Calculus AB formula sheet covers the core tools students use to analyze change, motion, area, and accumulation. It brings together limits, continuity, derivative rules, graph interpretation, integrals, and major theorems in one organized reference. Students need this cheat sheet to review formulas quickly and connect procedures to AP-style reasoning. It is especially useful when preparing for free-response questions that require both computation and explanation. The main ideas are built around limits, rates of change, and accumulated change. Limits support continuity, derivatives describe instantaneous rates and slopes, and integrals measure net accumulation or signed area. The Fundamental Theorem of Calculus connects derivatives and integrals through functions such as F(x)=axf(t)dtF(x)=\int_a^x f(t)\,dt. Many AP Calculus AB problems combine formulas with interpretation, units, and justification.

Key Facts

  • The limit definition of the derivative is f(x)=limh0f(x+h)f(x)hf'(x)=\lim_{h\to 0}\frac{f(x+h)-f(x)}{h}.
  • A function ff is continuous at x=ax=a when limxaf(x)=f(a)\lim_{x\to a}f(x)=f(a) and both sides of the equality exist.
  • The power rule is ddx(xn)=nxn1\frac{d}{dx}\left(x^n\right)=nx^{n-1} for real values of nn where the derivative is defined.
  • The product rule is ddx(uv)=uv+uv\frac{d}{dx}\left(uv\right)=u'v+uv' and the quotient rule is ddx(uv)=uvuvv2\frac{d}{dx}\left(\frac{u}{v}\right)=\frac{u'v-uv'}{v^2}.
  • The chain rule is ddx[f(g(x))]=f(g(x))g(x)\frac{d}{dx}\left[f(g(x))\right]=f'(g(x))g'(x).
  • A definite integral gives net accumulation, so abf(x)dx\int_a^b f(x)\,dx represents signed area or total change when ff is a rate.
  • The Fundamental Theorem of Calculus states that if F(x)=f(x)F'(x)=f(x), then abf(x)dx=F(b)F(a)\int_a^b f(x)\,dx=F(b)-F(a).
  • If A(x)=axf(t)dtA(x)=\int_a^x f(t)\,dt, then A(x)=f(x)A'(x)=f(x) wherever ff is continuous.

Vocabulary

Limit
A limit describes the value a function approaches as the input approaches a specified number.
Continuity
Continuity at x=ax=a means the function value exists, the limit exists, and limxaf(x)=f(a)\lim_{x\to a}f(x)=f(a).
Derivative
A derivative measures the instantaneous rate of change of a function and the slope of its tangent line.
Critical Point
A critical point occurs where f(x)=0f'(x)=0 or where f(x)f'(x) is undefined, provided f(x)f(x) is defined.
Definite Integral
A definite integral abf(x)dx\int_a^b f(x)\,dx measures signed area or net accumulated change over [a,b][a,b].
Fundamental Theorem of Calculus
The Fundamental Theorem of Calculus connects differentiation and integration by stating that accumulation functions have derivatives related to their integrands.

Common Mistakes to Avoid

  • Forgetting the chain rule, such as differentiating sin(3x)\sin(3x) as cos(3x)\cos(3x), is wrong because the inner derivative must be included, giving 3cos(3x)3\cos(3x).
  • Treating abf(x)dx\int_a^b f(x)\,dx as total area is wrong when f(x)f(x) is below the xx-axis because the definite integral gives signed area.
  • Using a derivative test without checking intervals is wrong because the sign of f(x)f'(x) must be analyzed on both sides of a critical point to justify increasing, decreasing, or extrema.
  • Assuming a function is continuous because it is defined at x=ax=a is wrong because continuity also requires limxaf(x)=f(a)\lim_{x\to a}f(x)=f(a).
  • Dropping the constant in an indefinite integral, such as writing 2xdx=x2\int 2x\,dx=x^2, is incomplete because the full family of antiderivatives is x2+Cx^2+C.

Practice Questions

  1. 1 Find ddx(x3sinx)\frac{d}{dx}\left(x^3\sin x\right).
  2. 2 Evaluate 142xdx\int_1^4 2x\,dx.
  3. 3 If A(x)=2xt2+1dtA(x)=\int_2^x \sqrt{t^2+1}\,dt, find A(3)A'(3).
  4. 4 Explain how the sign of f(x)f'(x) and the sign of f(x)f''(x) describe the shape and behavior of the graph of ff.