MathematicsA Level & IB

What is differentiation?

Differentiation is the process of finding the rate at which one quantity changes with respect to another — the gradient of a curve at a point.

Differentiation explained

When you differentiate a function you produce a second function, the derivative, whose value at any point equals the gradient of the original graph there. If yy measures distance and xx measures time, the derivative measures speed.
Most exam questions rely on a small set of rules: the power rule, the chain rule for functions inside functions, and the product and quotient rules for combinations. Differentiation then feeds straight into stationary points, tangents and normals, and optimisation.

Key formula

ddx(xn)=nxn1\dfrac{d}{dx}\left(x^{n}\right) = n x^{n-1}

Worked example

For y=3x4y = 3x^{4}, bring the power down and subtract one: dydx=12x3\dfrac{dy}{dx} = 12x^{3}. At x=2x = 2 the gradient is 9696.

Examiner tip

Rewrite roots and fractions as powers before differentiating — x\sqrt{x} becomes x1/2x^{1/2} and 1/x21/x^{2} becomes x2x^{-2}. Most lost marks come from skipping this step.

Differentiation: common questions

What is differentiation used for in real life?
Anywhere a rate of change matters: velocity and acceleration in mechanics, marginal cost in economics, reaction rates in chemistry, and optimisation problems such as minimising material used in packaging.
Is differentiation on the GCSE syllabus?
Formal differentiation is an A Level, IB and Additional Maths topic. GCSE Higher students meet the underlying idea as the gradient of a tangent drawn on a curve.

Related terms

Practise mathematics on MathsGradeUp

Take differentiation from a definition to full marks with exam-board question banks, revision notes and instant step-by-step feedback from Study Coach.

Related on MathsGradeUp

Keep studying

Practise it