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AP Calculus BC combines all major AB topics with advanced techniques for series, parametric curves, polar curves, and vector-valued motion. This cheat sheet helps students quickly review the formulas and tests most often needed for homework, quizzes, and AP exam practice. It is designed as a formula-forward reference so students can connect procedures with the meaning behind each result.

Core ideas include limits, differentiation, integration, accumulation, and approximation. BC students also need convergence tests, Taylor and Maclaurin series, arc length, polar area, and motion formulas. The most important habit is matching the structure of a problem to the correct formula, such as using dydx=dydtdxdt\frac{dy}{dx}=\frac{\frac{dy}{dt}}{\frac{dx}{dt}} for parametric curves or n=0an(xc)n\sum_{n=0}^{\infty} a_n(x-c)^n for power series.

Key Facts

  • The derivative definition is f(a)=limh0f(a+h)f(a)hf'(a)=\lim_{h\to 0}\frac{f(a+h)-f(a)}{h}, which gives the instantaneous rate of change at x=ax=a.
  • 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).
  • Integration by parts is udv=uvvdu\int u\,dv=uv-\int v\,du, and it is useful when a product contains functions that simplify after differentiation.
  • For parametric equations x=x(t)x=x(t) and y=y(t)y=y(t), the slope is dydx=dydtdxdt\frac{dy}{dx}=\frac{\frac{dy}{dt}}{\frac{dx}{dt}} when dxdt0\frac{dx}{dt}\ne 0.
  • The polar area formula is A=12αβr2dθA=\frac{1}{2}\int_{\alpha}^{\beta} r^2\,d\theta for a region traced once by r=f(θ)r=f(\theta).
  • A Taylor series centered at x=cx=c is n=0f(n)(c)n!(xc)n\sum_{n=0}^{\infty}\frac{f^{(n)}(c)}{n!}(x-c)^n.
  • The ratio test says a series an\sum a_n converges absolutely if limnan+1an<1\lim_{n\to\infty}\left|\frac{a_{n+1}}{a_n}\right|<1 and diverges if the limit is greater than 11.
  • Logistic growth has differential equation dPdt=kP(1PL)\frac{dP}{dt}=kP\left(1-\frac{P}{L}\right), where LL is the carrying capacity.

Vocabulary

Derivative
A derivative measures the instantaneous rate of change of a function and is written as f(x)f'(x) or dydx\frac{dy}{dx}.
Definite Integral
A definite integral abf(x)dx\int_a^b f(x)\,dx represents signed area, net change, or accumulated quantity over the interval [a,b][a,b].
Power Series
A power series is an infinite polynomial of the form n=0an(xc)n\sum_{n=0}^{\infty} a_n(x-c)^n centered at x=cx=c.
Radius of Convergence
The radius of convergence RR is the distance from the center cc over which a power series converges.
Parametric Curve
A parametric curve defines position using x=x(t)x=x(t) and y=y(t)y=y(t) instead of writing yy directly as a function of xx.
Polar Curve
A polar curve uses r=f(θ)r=f(\theta), where rr is distance from the pole and θ\theta is the angle from the polar axis.

Common Mistakes to Avoid

  • Using dydx=dydt\frac{dy}{dx}=\frac{dy}{dt} for parametric curves is wrong because slope compares vertical change to horizontal change. Use dydx=dydtdxdt\frac{dy}{dx}=\frac{\frac{dy}{dt}}{\frac{dx}{dt}}.
  • Forgetting the constant of integration in an indefinite integral is wrong because f(x)dx=F(x)+C\int f(x)\,dx=F(x)+C represents a family of antiderivatives.
  • Applying the ratio test and ignoring endpoints is wrong for power series because the test only gives the open interval of convergence. Check each endpoint separately.
  • Using rdθ\int r\,d\theta for polar area is wrong because the correct formula is A=12αβr2dθA=\frac{1}{2}\int_{\alpha}^{\beta} r^2\,d\theta.
  • Treating alternating series convergence as absolute convergence is wrong because (1)nan\sum (-1)^n a_n may converge conditionally even when an\sum |a_n| diverges.

Practice Questions

  1. 1 Find dydx\frac{dy}{dx} for the parametric curve x=t2+1x=t^2+1 and y=t34ty=t^3-4t at t=2t=2.
  2. 2 Evaluate 016xe3x2dx\int_0^1 6xe^{3x^2}\,dx.
  3. 3 Find the radius of convergence of n=1(x2)nn3n\sum_{n=1}^{\infty}\frac{(x-2)^n}{n3^n}.
  4. 4 Explain why a power series can converge at one endpoint of its interval of convergence but diverge at the other endpoint.

Understanding AP Calculus BC Formula Sheet

A formula becomes useful only when its quantities have a clear job. A derivative can describe speed, population change, temperature change, or the steepness of a graph. Its units reveal the meaning.

If position is measured in meters and time in seconds, velocity is measured in meters per second. A second derivative then tells how velocity changes. Definite integrals work in the opposite direction by combining many tiny changes into a total.

The signed area under a velocity graph gives displacement, while total distance requires separating intervals where velocity is negative. This difference is a common source of lost points.

Series problems require more judgment than memorization. Before choosing a convergence test, inspect the terms. Geometric series have a constant ratio.

Terms with factorials or powers often respond well to the ratio test. Positive decreasing terms with a logarithm may suggest the integral test. Alternating terms need checks for decreasing size and a limiting value of zero.

A convergent series has a finite sum, but a power series has another feature. It behaves differently at different input values. The radius of convergence gives the central interval, yet each endpoint must be tested separately.

Taylor polynomials are local approximations, so they are usually most accurate near their center. The next omitted term can often estimate the error when the required conditions hold.

Parametric and polar forms describe paths that can be awkward in ordinary coordinate form. In parametric motion, time orders the points on a curve. A particle can pass through the same location more than once with different velocities.

This makes direction important. To find acceleration, first find the horizontal and vertical velocity components, then differentiate each with respect to time. For polar curves, a negative radius places a point in the opposite direction from the stated angle.

Sketching a few angles before integrating can prevent counting the wrong region. When finding area between two polar curves, determine which curve is farther from the origin on the chosen interval. For arc length, use the speed of the moving point, not just a visual estimate from the graph.

Logistic models show why a differential equation can tell a realistic story. Early in the model, growth is close to exponential because the population is small compared with its limit. Growth then slows as the population approaches carrying capacity.

The graph has an inflection point when the population reaches half of the carrying capacity, where growth is fastest. Real populations may not follow this model exactly because food supply, migration, disease, and seasons can change.

On assessments, pay close attention to initial conditions, interval endpoints, and whether a result represents a rate, a total change, or an average value. A formula sheet is most helpful after you have labeled these meanings first.