Unit 6Antiderivatives for Basic Functions
Concept 4.109Built for May 2027 AP Exam

Antiderivatives for Basic Functions

Reviewed by ACEpath AP Math Editorial Team

Last Updated: September 2026

30-second summary

An antiderivative reverses a derivative, and the reverse power rule is the engine: raise the exponent by one and divide by the new exponent. The exception is x−1x^{-1}, whose antiderivative is the natural logarithm, because raising −1-1 by one gives zero and division by zero is unavailable. Sine, cosine, and the exponential each reverse with a sign to track or none at all. Every indefinite integral carries a constant, since shifting a function vertically leaves every slope unchanged. On the exam the skill rarely appears as its own part; it sits inside evaluation problems, where a wrong antiderivative destroys a computation that was otherwise correct.

On the AP Exam

AP Calculus AB tests this skill through the representations and reasoning described below.

What you’ll see
Mostly indirect use. A no-calculator part asks for a total from a polynomial rate, and the antiderivative is the first step. Occasionally an item asks directly for ∫f(x) dx\int f(x)\,dx and offers four candidate families.
What you’ll do
Reverse one rule at a time, check the result by differentiating it back, and keep the constant when the integral has no limits.
Memory hook
Up one, divide by the new one. The exponent rises by one and the same number lands underneath.
Use it on the exam
For MCQs: Differentiate the choices instead of integrating. Only one candidate will return the integrand, and the check takes less time than the computation. For FRQs: When the antiderivative is a step inside a larger part, differentiate your answer in the margin before you use it. One line of checking prevents an error that would otherwise cost every point in the part.

Concept Review

A Family, Not a Function

Figure 1 — Every curve in the family has the same slope at the same xx, so all of them are antiderivatives of the same function. The constant only decides which one you are standing on.

If F′(x)=f(x)F'(x) = f(x) on an interval, then FF is an antiderivative of ff there, and so is F(x)+CF(x) + C for any constant CC. The indefinite integral records the whole family:

∫f(x) dx=F(x)+C\int f(x)\,dx = F(x) + C

A definite integral does not need the constant, because the two evaluations cancel it. An indefinite integral does, and dropping it is a scoring error rather than a stylistic one.

Every curve in the family has the same slope at the same $x$, so all of them are antiderivatives of the same function. The constant only decides which one you are standing on.

The Rules Worth Memorizing

IntegrandAntiderivativeCheck by differentiating
xnx^{n}, n≠−1n \ne -1xn+1n+1+C\frac{x^{n+1}}{n+1} + C(n+1)xnn+1=xn(n+1)\frac{x^{n}}{n+1} = x^{n}
x−1=1xx^{-1} = \frac{1}{x}ln⁡∣x∣+C\ln\lvert x \rvert + C1x\frac{1}{x}
kk, a constantkx+Ckx + Ckk
exe^{x}ex+Ce^{x} + Cexe^{x}
cos⁡x\cos xsin⁡x+C\sin x + Ccos⁡x\cos x
sin⁡x\sin x−cos⁡x+C-\cos x + Csin⁡x\sin x
sec⁡2x\sec^{2} xtan⁡x+C\tan x + Csec⁡2x\sec^{2} x

Two of these deserve a note. The absolute value in ln⁡∣x∣\ln\lvert x \rvert keeps the antiderivative defined on intervals where xx is negative, and the exam accepts either form when the domain is positive. The minus sign in −cos⁡x-\cos x is the most frequently dropped symbol in the whole unit, and it is invisible in a final answer that is only checked for plausibility.

Linear Inner Functions

The chain rule leaves a trace that can be reversed when the inner function is linear:

∫f(ax+b) dx=1aF(ax+b)+C\int f(ax + b)\,dx = \frac{1}{a}F(ax + b) + C

So ∫e3x dx=13e3x+C\int e^{3x}\,dx = \frac{1}{3}e^{3x} + C and ∫cos⁡(2x) dx=12sin⁡(2x)+C\int \cos(2x)\,dx = \frac{1}{2}\sin(2x) + C. The factor is the reciprocal of the inner slope, and it is easy to test: differentiate the answer and watch the factor cancel. When the inner function is not linear, this shortcut fails, which is why ∫ex2 dx\int e^{x^2}\,dx has no elementary form at all.

Functions With No Elementary Antiderivative

Many continuous functions cannot be antidifferentiated in closed form. The standard examples are e−x2e^{-x^2}, sin⁡(x2)\sin\left(x^2\right), sin⁡xx\frac{\sin x}{x}, and 1+x3\sqrt{1 + x^3}. This is not a gap in your technique; it is a theorem about which elementary expressions have elementary integrals. On the exam these appear only inside definite integrals, where a graph, a table, or a calculator supplies the value, and the correct response is never to search for a formula.

Checking Is a One-Line Habit

Every antiderivative can be verified by differentiating it. The habit costs a single line and catches sign errors, exponent errors, and missing reciprocal factors at once. In a multi-step FRQ the check also protects the later parts, because an antiderivative that is wrong by a constant multiple silently scales every subsequent answer.

Common Misconception Check

  • Myth 1: “∫x−1 dx=x00\int x^{-1}\,dx = \frac{x^{0}}{0}.” Truth: That expression is undefined. The antiderivative of x−1x^{-1} is ln⁡∣x∣\ln\lvert x \rvert, and this is the single exception the power rule cannot cover.
  • Myth 2: “The +C+C is decoration.” Truth: It is the difference between a family and a member. Any part that asks for a particular solution depends on it.
  • Myth 3: “Every continuous function has an antiderivative you can write down.” Truth: Every continuous function has an antiderivative. Very few have one built from elementary functions.

Topic-Specific Study Method

Reverse One Rule, Then Check

Borrowed idea: Reverse the rules, then check. Antidifferentiation is differentiation read backwards. The table is the same, and the direction is the only change. Raise the exponent, divide by the new number, and differentiate to confirm. One line of checking beats ten of hoping. The check catches sign errors, exponent errors, and missing reciprocal factors at once, and it costs less time than rereading the work you have just written.

Exam disguiseWhat you see on the pageWhat your brain must translateRequired execution
“Evaluate the integral” with a polynomialpowers and coefficientsreverse power ruleraise, divide, check
A rate given as a polynomial“how many words by the end”antiderivative then subtractconstant term becomes kxkx
Choices that are functionsfour candidate familiesdifferentiate eachpick the one returning the integrand
1x\frac{1}{x} in the integranda negative powerthe logarithm caseabsolute value, plus CC
A composite like e3xe^{3x}a linear inner functionreciprocal factordivide by the inner slope

① Raise the exponent before doing anything else. Writing the new exponent down first prevents the classic slip of dividing by the old one.

② Handle the constant term separately. A bare number integrates to that number times xx, not to zero and not to a higher power.

③ Differentiate the answer. If the result is not the integrand, the error is in the exponent or in a sign, and both are visible in one line.


Training & Error Diagnosis

Core Archetype (Simplest Form): Find ∫(6x2−4x+5)dx\int\left(6x^{2} - \frac{4}{x} + 5\right)dx.

Standard Execution:

  1. Power term. ∫6x2 dx=2x3\int 6x^{2}\,dx = 2x^{3}.
  2. Logarithm term. ∫4x dx=4ln⁡∣x∣\int \frac{4}{x}\,dx = 4\ln\lvert x \rvert.
  3. Constant term. ∫5 dx=5x\int 5\,dx = 5x.
  4. Assemble. 2x3−4ln⁡∣x∣+5x+C2x^{3} - 4\ln\lvert x \rvert + 5x + C.
  5. Check. Differentiating gives 6x2−4x+56x^{2} - \frac{4}{x} + 5, which matches.

Exam Variation (Context / Parameter Shift): A teacher reads at a rate modeled by W(t)=−3t2+8t+100W(t) = -3t^{2} + 8t + 100 words per minute for 0≤t≤100 \le t \le 10. Find the total number of words read in the ten minutes.

Solution: An antiderivative is F(t)=−t3+4t2+100tF(t) = -t^{3} + 4t^{2} + 100t. Then F(10)=−1000+400+1000=400F(10) = -1000 + 400 + 1000 = 400 and F(0)=0F(0) = 0, so the total is 400400 words. Two checks are worth doing: the units are words because a rate in words per minute was integrated over minutes, and differentiating FF returns WW exactly, which confirms that the constant term became 100t100t rather than disappearing.

Common Traps & Failure Signals:

  1. Dividing by the old exponent (Signal: a coefficient of 6x36x^{3} from 6x26x^{2}): divide by the new exponent, which is the one you just wrote.
  2. Constant term vanished (Signal: an antiderivative with no linear term when the integrand had a constant): a constant integrates to kxkx.
  3. Missing constant (Signal: an indefinite integral with no +C+C): the family needs it.

6D Cognitive Error Diagnosis (Where Your Thinking Broke):

  • Exponent Off By One: Write the new exponent first.
  • Sign Dropped: You integrated sin⁡x\sin x to cos⁡x\cos x and lost the minus, which is not a memory lapse but a direction error, since the derivative of cos⁡\cos carries the minus and reversing must carry it too.
  • Constant Ignored: You treated a bare number as if it integrated to nothing, so the antiderivative is off by a linear term that looks harmless on a graph and changes the value of every definite integral built on it.

Past 10-Year AP Exam Appearance

Testing Frequency
Rare in FRQs
Two of the nine released exams since 2017 contain a part in which producing an antiderivative from the basic rules is the scored step, and both are no-calculator parts
10-Year Total Count
2 of 9 Exams · 2 FRQ Parts
The skill otherwise appears inside other parts and dominates the multiple-choice section, where the reverse power rule is tested directly
FRQ Years Appeared
2019 (Q3b), 2025 (Q3D) ---

Practice Examples

MCQ 1

The Reverse Power Rule

∫(8x3−6x)dx=\int\left(8x^{3} - 6x\right)dx =

MCQ 2

The Logarithm Case

∫5x dx=\int \frac{5}{x}\,dx =

MCQ 3

A Composite With a Linear Inside

∫cos⁡(4x) dx=\int \cos(4x)\,dx =

FRQ 4

From a Rate to a Total

A pump moves water at a rate modeled by r(t)=12−3t2r(t) = 12 - 3t^{2} gallons per minute for 0≤t≤20 \le t \le 2 minutes.

(a) Find ∫r(t) dt\int r(t)\,dt.

(b) Find the total volume of water moved during the two minutes.

(c) A student claims that ∫02r(t) dt\int_0^{2} r(t)\,dt is the area of the region between the graph of rr and the tt-axis. Explain why the claim is true here and would fail if r(t)=12−3t2r(t) = 12 - 3t^{2} were replaced by 12−12t212 - 12t^{2}.

Cheatsheet

Core Reference

AntiderivativeFrequent error
xnx^{n}, n≠−1n \ne -1xn+1n+1+C\frac{x^{n+1}}{n+1} + Cdividing by nn
1x\frac{1}{x}ln⁡∣x∣+C\ln\lvert x \rvert + Capplying the power rule
kkkx+Ckx + Cdropping the xx
exe^{x}ex+Ce^{x} + Cnone
cos⁡x\cos xsin⁡x+C\sin x + Cnone
sin⁡x\sin x−cos⁡x+C-\cos x + Closing the minus
f(ax+b)f(ax+b)1aF(ax+b)+C\frac{1}{a}F(ax+b) + Cmultiplying by aa

Sentences That Score

TOPIC REVIEW • NEXT STEP IN YOUR LEARNING LOOP

Ready to check your understanding?

Strengthen this topic with AP-style practice, or continue to next topic.