Chapter 2: Curve-sketching using the derivative Notes

Use the first and second derivatives to find where a curve increases and decreases, its stationary points and points of inflection, global maxima and minima, optimisation problems, and primitive functions.

Sections

  1. 2A Increasing, decreasing and stationary at a point Mastered

    Using the sign of the derivative to decide whether a curve is increasing, decreasing or stationary at a point, finding where a function increases or decreases, and what this says about x-intercepts.

  2. 2B Stationary points and turning points Mastered

    Maximum and minimum turning points and stationary points of inflection, local maxima and minima, classifying stationary points with a table of slopes, and finding unknown coefficients from a stationary point.

  3. 2C Some less familiar curves Mastered

    Using the derivative on rational functions with asymptotes and discontinuities, and recognising vertical tangents and cusps where the derivative is undefined.

  4. 2D Second and higher derivatives Mastered

    The second, third and higher derivatives of a function, their notations, and finding successive derivatives of polynomials, negative powers and composite functions.

  5. 2E Concavity and points of inflection Mastered

    Concave up and concave down, using the second derivative to find concavity and points of inflection, and the second-derivative test for classifying stationary points.

  6. 2F Systematic curve sketching with the derivative Mastered

    A step-by-step routine for sketching curves: domain, symmetry, intercepts, asymptotes, stationary points and inflections, and using the sketch to solve polynomial inequations.

  7. 2G Global maximum and minimum Mastered

    The difference between local and global maxima and minima, and finding the global maximum and minimum of a function on a closed interval by checking stationary points and endpoints.

  8. 2H Continuity and differentiability Mastered

    What it means for a function to be continuous or differentiable at a point, testing piecewise-defined functions at the join, corners, cusps and vertical tangents, and finding constants that make a join smooth.

  9. 2I Applications of maximisation and minimisation Mastered

    A step-by-step method for optimisation problems: choosing a variable, writing the quantity as a function of one variable, finding and testing stationary points, checking endpoints, and answering in context.

  10. 2J Maximisation and minimisation in geometry Mastered

    Optimisation problems in geometry: shapes inscribed under curves and inside solids, using similar triangles or Pythagoras to link the variables, and minimising distance by minimising its square.

  11. 2K Primitive functions Mastered

    Reversing differentiation: primitives of powers of x including negative and fractional powers, the arbitrary constant, finding a particular primitive from an initial condition, and working back from a second derivative.

Formula sheet