The derivative is the gradient of the curve and the instantaneous rate of change. In AI SL you differentiate terms (including negative ) with , then use for the gradient at a point, tangents and normals, where a function increases or decreases, and maximum or minimum values.
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Multiply by the power and reduce the power by one: . Differentiate a sum term by term; a constant term differentiates to 0. Rewrite fractions as powers first: , whose derivative is .
The gradient at a point
Substitute into , not . For , and the gradient at is . To find where the gradient has a given value, solve .
Tangents and normals
The tangent at has gradient and passes through ; the normal has gradient . For the curve above at : , so the tangent is .
Increasing and decreasing
is increasing where and decreasing where . Sketch on the GDC to see where it is above or below the axis.
Maximum and minimum points
At a turning point . Solve it (by hand or on the GDC) and check the sign of either side: then is a maximum, then a minimum. Optimisation questions build the function from the context first, then do exactly this.
Key formulas
Derivative of In the booklet
Constant multiples, sums Learn it
Gradient of tangent at Learn it
Gradient of normal Learn it
Increasing / decreasing Learn it
Stationary points; optimisation Learn it
The IB formula booklet is provided in every exam paper. In the booklet = printed there, so know where to find it; Learn it = not in the booklet, so learn it by heart. All AI SL formulas →
Worked example 1: Power rule and evaluating · easy
. Find and the exact gradient at .
Solution
1. Power rule: multiply coefficient by the power, drop the power by 1.
2. Differentiate: .
3. Substitute: .
4. Evaluate: .
4 steps
Examiner tip: The derivative of a constant (here ) is zero — a horizontal line has no gradient. The derivative of is simply .
Worked example 2: Finding given a specific gradient · medium
. Find the exact values of where the gradient equals .
Solution
1. Derivative: .
2. Set equal to : .
3. Rearrange: .
4. Simplify: .
5. Factorise: .
6. State: .
6 steps
Examiner tip: "Gradient equals " means set the DERIVATIVE equal to , not the original function.
Worked example 3: Finding constants from a point and a gradient · hard
Curve passes through and has gradient at . Find and exactly.
Solution
1. Point equation: substitute into the curve .
2. Derivative: .
3. Gradient equation: at , .
4. Subtract: .
5. Solve: .
6. Back-substitute: . So .
5. Solve: .
6 steps · 1 to fill in
Examiner tip: A point tells you about ; a gradient tells you about . Keep the two substitutions separate when building simultaneous equations.
Differentiation exam-style questions
3 questions from our AI SL bank, written in the style of IB papers, easiest first. One has its full worked solution open here. Open the worked answer, or check your answer in the practice area.
Examiner's noteCalculus: not differentiating, f(a) for f′(a), and the derivative as a rate
Where marks are lost: Candidates used a normal's gradient as the tangent's, never differentiated, found f(1) where f′(1) was needed, stopped at f′(1) without writing the tangent's equation, ignored an instruction to use their derivative, stopped at the x-coordinate of a minimum, described a derivative as a height or an average rate, and left out the constant of integration.
Examiners flagged this in 3 exam series (May 2024, November 2024, November 2025). Summarised in our own words from IB subject reports, IB Programme Resource Centre. Read the full note →
Differentiation on your calculator
A GDC is allowed on every AI paper. Keystrokes for the Casio fx-CG50, TI-84 Plus CE and TI-Nspire, with a checked worked example:
Do I need the chain rule or product rule in AI SL?
No. AI SL differentiates terms of the form axⁿ (n an integer). The chain, product and quotient rules are in AA, and in AI HL.
What is the difference between f(2) and f′(2)?
f(2) is the y-value of the curve at x = 2. f′(2) is the gradient of the curve there. Tangent and normal questions need both.
How many IB Maths AI SL differentiation rules questions are there?
There are 28 exam-style differentiation rules questions in the AI SL question bank (Paper 1: 23 · Paper 2: 5), graded 8 easy, 13 medium, 4 hard, 3 very hard. Every question has a full IB-style mark scheme (M, A and R marks).
Is differentiation rules on Paper 1 or Paper 2?
Both. In the bank, Paper 1: 23 · Paper 2: 5. Practise with your GDC — AI papers expect calculator methods throughout.