Salam Academy
Paper 1 · Module

Differentiation

5 subtopics≈ 220 min in total
  1. Gradients and the power rule

    What the gradient of a curve means, how chords close in on the tangent, and the power rule ddxxn=nxn−1\dfrac{d}{dx}x^n=nx^{n-1} that makes differentiating fast, including roots, fractions and second derivatives.

    ≈ 45 min
  2. The chain rule

    How to differentiate a function of a function, such as (2x−5)4(2x-5)^4 or x2+5\sqrt{x^2+5}, without multiplying out: differentiate the outside, keep the inside, and multiply by the derivative of the inside.

    ≈ 40 min
  3. Tangents and normals

    Using dydx\dfrac{dy}{dx} to find the equation of the tangent and the normal to a curve at a point, points where the tangent has a given gradient, and the follow-on problems examiners love.

    ≈ 40 min
  4. Stationary points and increasing functions

    Where a curve turns: finding stationary points with dydx=0\dfrac{dy}{dx}=0, deciding whether each is a maximum or minimum with the second derivative, and finding where a function is increasing or decreasing.

    ≈ 45 min
  5. Optimisation and rates of change

    Using derivatives to answer real questions: the largest area, the smallest surface, the cheapest design, and how fast one quantity changes when another one does.

    ≈ 50 min