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IB Maths AA HL · Unit 5: Calculus

IB Maths AA HL Advanced Integration Questions

Exam-style IB Maths AA HL advanced integration questions with worked solutions. Start with the 3 fully worked examples below — each is solved step by step the way an IB examiner expects — then try the practice questions and check your working against the mark scheme.

Practise Advanced Integration questions → AA HL formula booklet

What you need to know

V = π ∫ y² dx (about the x-axis) or V = π ∫ x² dy (about the y-axis). HL AA extends to improper integrals with limits at infinity. Volumes of revolution and improper integrals overview →

∫u·dv = uv - ∫v·du, with the LIATE rule for picking u. HL AA Paper 3 loves cyclic integrals like ∫e^x·sin(x) dx where you apply parts twice. Integration by parts and cyclic integrals overview →

What's examined in AA HL advanced integration

The question bank covers these advanced integration question types (number of questions in brackets):

Key formulas

Standard integrals (HL)
\(\int \dfrac{1}{\sqrt{a^2-x^2}}\, dx = \arcsin\!\tfrac{x}{a} + C,\ \int \dfrac{1}{a^2 + x^2}\, dx = \tfrac{1}{a}\arctan\!\tfrac{x}{a} + C\)
Integration by parts
\(\int u\, dv = uv - \int v\, du\)
Volume of revolution (about x-axis)
\(V = \pi \int_a^b y^2\, dx\)
Volume of revolution (about y-axis)
\(V = \pi \int_c^d x^2\, dy\)

In the same notation as the IB formula booklet. All AA HL formulas →

Advanced Integration worked examples

Worked example 1: Integration by substitution · easy

Find the exact value of the definite integral $\int_0^1 x e^{x^2} \, dx$.

Solution

1. Identify the inner function and set up the substitution: Let $u = x^2$.

2. Differentiate to find the differential relationship: $\frac{du}{dx} = 2x \implies dx = \frac{du}{2x}$.

3. Calculate the new limits of integration in terms of $u$: When $x = 0$, $u = 0^2 = 0$. When $x = 1$, $u = 1^2 = 1$.

4. Substitute $u$, $dx$, and the new limits into the integral: $\int_0^1 x e^u \frac{du}{2x}$.

5. Cancel the $x$ terms and factor out the constant: $\frac{1}{2} \int_0^1 e^u \, du$.

6. Evaluate the definite integral using the anti-derivative: $\frac{1}{2} [e^u]_0^1 = \frac{1}{2}(e^1 - e^0) = \mathbf{\frac{1}{2}(e - 1)}$.

Examiner tip: When using integration by substitution for definite integrals, always convert the upper and lower limits to be in terms of $u$. If you leave them as $x$-values while integrating with respect to $u$, your evaluation will be completely incorrect.

Worked example 2: Integration by parts · medium

Use integration by parts to find the exact value of $\int_1^e x \ln x \, dx$.

Solution

1. Select $u$ and $dv$ using the LATE hierarchy (Logarithmic before Algebraic): Let $u = \ln x$ and $dv = x \, dx$.

2. Differentiate $u$ and integrate $dv$: $du = \frac{1}{x} \, dx$ and $v = \frac{x^2}{2}$.

3. State the integration by parts formula: $\int u \, dv = uv - \int v \, du$.

4. Substitute the expressions into the formula: $\left[ \frac{x^2}{2} \ln x \right]_1^e - \int_1^e \frac{x^2}{2} \cdot \frac{1}{x} \, dx$.

5. Simplify and evaluate the remaining integral: $\left[ \frac{x^2}{2} \ln x \right]_1^e - \int_1^e \frac{x}{2} \, dx = \left[ \frac{x^2}{2} \ln x - \frac{x^2}{4} \right]_1^e$.

6. Substitute the limits to find the exact value: $\left(\frac{e^2}{2}(1) - \frac{e^2}{4}\right) - \left(0 - \frac{1}{4}\right) = \frac{e^2}{4} + \frac{1}{4} = \mathbf{\frac{e^2 + 1}{4}}$.

Examiner tip: The "LATE" acronym (Log, Algebra, Trig, Exponential) dictates which function should be $u$. Assigning $dv = \ln x \, dx$ traps you, as you cannot easily integrate it without using parts a second time!

Worked example 3: Volumes of revolution with partial fractions · hard

The region enclosed by the curve $y = \frac{1}{\sqrt{x^2 - 4}}$, the $x$-axis, and the vertical lines $x=3$ and $x=5$ is rotated $360^\circ$ about the $x$-axis. Find the exact volume of the solid generated.

Solution

1. State the formula for a volume of revolution about the $x$-axis: $V = \pi \int_a^b y^2 \, dx$.

2. Square the function and set up the integral: $V = \pi \int_3^5 \frac{1}{x^2 - 4} \, dx$.

3. Factorise the denominator and split into partial fractions: $\frac{1}{(x-2)(x+2)} \equiv \frac{A}{x-2} + \frac{B}{x+2}$. Solving gives $A = \frac{1}{4}$ and $B = -\frac{1}{4}$.

4. Rewrite the integral using the partial fractions: $V = \frac{\pi}{4} \int_3^5 \left( \frac{1}{x-2} - \frac{1}{x+2} \right) \, dx$.

5. Integrate to log forms: $\frac{\pi}{4} \big[ \ln|x-2| - \ln|x+2| \big]_3^5$.

6. Evaluate the limits and simplify using log laws: $\frac{\pi}{4} \big( (\ln 3 - \ln 7) - (\ln 1 - \ln 5) \big) = \frac{\pi}{4} \big( \ln \frac{3}{7} + \ln 5 \big) = \mathbf{\frac{\pi}{4} \ln\left(\frac{15}{7}\right)}$.

Examiner tip: Ensure you physically square the function $y$ before attempting to decompose it into partial fractions. Doing partial fractions on $y$ and then squaring the result creates cross-terms that are much harder to integrate!

Try these IB Maths AA HL advanced integration questions

Three questions from the bank, easiest first. Mark schemes and AI marking of your written working are in the practice area.

Question 2 · medium · 5 marks · Paper 1

Using integration by parts, evaluate: \[\int \ln x \, dx\] (Hint: Let \(u = \ln x\) and \(\frac{dv}{dx} = 1\)).

Attempt it and see the mark scheme →

All 50 advanced integration questions with mark schemes →

FAQ

How many IB Maths AA HL advanced integration questions are there?

There are 50 exam-style advanced integration questions in the AA HL question bank (Paper 1: 44 · Paper 2: 6), graded 7 easy, 21 medium, 14 hard, 8 starter. Every question has a full IB-style mark scheme (M, A and R marks).

Is advanced integration on Paper 1 or Paper 2?

Both. In the bank, Paper 1: 44 · Paper 2: 6. Paper 1 is non-calculator, so practise the exact-value algebra as well as the GDC methods.

Where can I get the mark schemes?

Open the AA HL Unit 5 practice page: every question has a step-by-step IB-style mark scheme, and you can photograph your working for instant AI marking. The worked examples on this page are free.

More AA HL Unit 5 topics

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