Salam Academy
Paper 1 · Module

Differentiation

10 subtopics≈ 435 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. 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
  3. 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
  4. 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
  5. Derivatives of eˣ, ln x and trigonometric functions

    The derivatives of exe^x, ln⁡x\ln x, sin⁡x\sin x, cos⁡x\cos x and tan⁡x\tan x, why they need radians, and how to combine them with the chain rule for functions like e3xe^{3x}, ln⁡(x2+1)\ln(x^2+1) and sin⁡2x\sin^2x.

    ≈ 40 min
  6. 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
  7. The product and quotient rules

    How to differentiate two functions multiplied together, uvuv, or divided, uv\dfrac uv, and how to tidy the result by factorising, so it is ready for finding stationary points.

    ≈ 45 min
  8. Implicit differentiation

    Differentiating curves like x2+xy+y2=12x^2+xy+y^2=12 that can't easily be written as y=…y=\ldots: differentiate every term with respect to xx, remembering that yy terms pick up a factor dydx\dfrac{dy}{dx}.

    ≈ 45 min
  9. Parametric differentiation

    Curves described by a third variable tt: x=f(t)x=f(t), y=g(t)y=g(t). How to find their gradient with dydx=dy/dtdx/dt\dfrac{dy}{dx}=\dfrac{dy/dt}{dx/dt}, and how to find tangents and special points.

    ≈ 40 min
  10. Stationary points and tangents

    Putting the Pure 2/3 rules to work: finding exact stationary points of curves like y=xe2xy=xe^{2x} and y=ln⁡xxy=\dfrac{\ln x}{x}, deciding their nature, and finding tangents and normals.

    ≈ 45 min