1. Find dy/dx when y = 4/(3x − 1)2.
- A−24/(3x − 1)3
- B−8/(3x − 1)3
- C24/(3x − 1)3
- D−24/(3x − 1)2
Show answer
Answer: A. y = 4(3x − 1)−2, so dy/dx = 4 × (−2)(3x − 1)−3 × 3 = −24/(3x − 1)3. Both the −2 and the chain-rule factor 3 are needed.
By Team Megalecture · Updated 4 Nov 2026
87 exam-style questions on Pure Mathematics 1, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
87 questions · 8 topics · 10 per test
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
Answer: A. y = 4(3x − 1)−2, so dy/dx = 4 × (−2)(3x − 1)−3 × 3 = −24/(3x − 1)3. Both the −2 and the chain-rule factor 3 are needed.
Answer: C. No real roots needs b2 − 4ac < 0: 16 − 4k2 < 0, so k2 > 4, giving k < −2 or k > 2. Sketch y = k2 − 4 to get the outside region, not the inside.
Answer: C. The radius from (1, 2) to (4, 6) has gradient 4/3, so the tangent (perpendicular to the radius) has gradient −3/4. y − 6 = −3/4 (x − 4) gives 4y − 24 = −3x + 12, i.e. 3x + 4y = 36.
Answer: D. Use sin2θ + cos2θ = 1: the numerator is sin2θ. Then sin2θ/(sin θ cos θ) = sin θ/cos θ = tan θ.
Answer: C. f′(x) = 3x2 − 12x + 9 = 3(x − 1)(x − 3). Increasing where f′(x) > 0, which is outside the roots: x < 1 or x > 3.
Answer: D. 6/√x = 6x−1/2. Integrating: 6x1/2/(1/2) + c = 12√x + c. Dividing by 1/2 doubles the coefficient.
Answer: D. u1 = S1 = 5 and u2 = S2 − S1 = 14 − 5 = 9, so d = 9 − 5 = 4. In general the n2 coefficient is d/2.
Answer: B. π rad = 180°, so 3π/8 = 3 × 180°/8 = 67.5°.
Answer: B. Write −2/x as −2x−1. Its derivative is (−2)(−1)x−2 = +2/x2, so dy/dx = 12x3 + 2/x2. The two negatives make a plus.
Answer: C. Perimeter = two radii + arc = 2 × 5 + 5 × 1.6 = 10 + 8 = 18 cm. The common slip is forgetting one or both radii.
87, each with the answer and a short explanation, across 8 topics: Quadratics, Functions, Coordinate geometry, Circular measure, Trigonometry, Series, Differentiation, Integration. Every chapter test draws ten of them, so you can take it many times.
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.