CSEC ADDITIONAL MATHEMATICS · SECTION 3 · LESSON C2

The Chain, Product and Quotient Rules

Differentiating composite functions with the chain rule, products with the product rule and quotients with the quotient rule, including trigonometric functions.

Introductory CalculusS3 A.7S3 A.8≈ 45 min🎮 3 games
Before you start

By the end of this lesson you can…

Step 1 · Watch

Explainer video

5 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.

LESSON C2 · EXPLAINER

The Chain, Product and Quotient Rules

Most functions you meet are built from others: a sine of a polynomial, a polynomial times a sine, a ratio of two polynomials. Three rules handle them all.

Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.

Step 2 · Read

Key notes

Copy these into your notebook in your own words — that is how they stick.

Chain rule

dy/dx = dy/du × du/dx.

Power of a function

d/dx[f(x)]ⁿ = n[f(x)]ⁿ⁻¹ f′(x).

Product rule

d/dx(uv) = u v′ + v u′.

Quotient rule

d/dx(u/v) = (v u′ − u v′)/v².

Trig

d/dx sin(g) = g′ cos g; d/dx cos(g) = −g′ sin g.

Combining

Product with a chain factor: differentiate each factor with the chain rule.

Simplify

Factorise and cancel common factors in the answer.

Notation

u, v, u′, v′ clearly labelled earns the method mark.

EXAM TIPS & COMMON MISTAKES

  • In the quotient rule the order matters: v u′ MINUS u v′ — the bottom first.
  • For (ax + b)ⁿ the derivative includes the factor a: d/dx(2x + 3)⁵ = 5·2·(2x + 3)⁴.
  • Write u, v, u′ and v′ in a table before substituting.
  • Do not expand before differentiating a power such as (2x + 1)⁵ — use the chain rule.
Play & practise

Games

3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness. More games in the Additional Mathematics Arcade.

Step 3 · Practise

Paper 1 practice — multiple choice

8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.

CSEC Paper 01 style · SO A.7

1. If y = (2x + 3)⁵ then dy/dx is

Answer: C. Chain rule gives a factor 2.
CSEC Paper 01 style · SO A.7

2. d/dx sin(x² + 1) is

Answer: D. cos(x² + 1) × 2x.
CSEC Paper 01 style · SO A.8

3. If y = x² sin x then dy/dx is

Answer: A. Product rule.
CSEC Paper 01 style · SO A.8

4. If y = (x + 1)/(x − 2) then dy/dx is

Answer: B. [(x − 2) − (x + 1)]/(x − 2)².
CSEC Paper 01 style · SO A.7

5. d/dx (cos³x) is

Answer: C. 3 cos²x × (−sin x).
CSEC Paper 01 style · SO A.7

6. d/dx √(3x² + 1) is

Answer: D. ½(3x² + 1)^{−1/2} × 6x.
CSEC Paper 01 style · SO A.8

7. If y = sin x / x then dy/dx is

Answer: A. Quotient rule.
Adapted from CSEC P1 May/June 2024 (differentiation item)

8. If y = 5/(2 − x), then dy/dx is

Answer: B. 5(2 − x)⁻¹ → 5(2 − x)⁻² (the inner derivative −1 cancels the minus).
Step 4 · Apply

Paper 2 practice — structured questions

Write full answers, then reveal the mark scheme and tick the points you earned (23 marks in total). Show all your working — method marks count. Your answers are saved on this device.

CSEC Paper 02 style · Section 3 (Rules of differentiation)

Question 1 [12 marks]

Differentiate each of the following with respect to x, simplifying where possible.

(a) y = (3x − 2)⁵ [2]

MARK SCHEME — (a) (max 2)

(b) y = x³ cos 2x [3]

MARK SCHEME — (b) (max 3)

(c) y = (2x + 1)/(x² + 1) [4]

MARK SCHEME — (c) (max 4)

(d) y = √(4x² + 9) [3]

MARK SCHEME — (d) (max 3)

CSEC Paper 02 style · Section 3 (Using the rules)

Question 2 [11 marks]

Answer all parts.

(a) Differentiate y = sin²3x and show that dy/dx = 3 sin 6x. [4]

MARK SCHEME — (a) (max 4)

(b) Differentiate y = (x² + 1)/(x − 1). [3]

MARK SCHEME — (b) (max 3)

(c) Find the coordinates of the stationary points of y = x²/(x − 2). [4]

MARK SCHEME — (c) (max 4)

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Sources

Where this topic appears in CSEC papers

Find these in your own past-paper booklets for extra timed practice. Items above are written in the style of these papers; any adapted from a specific question say so.