What is the domain?
Which input values are allowed? Restrictions can come from denominators, roots, logarithms or the model itself.
MATHEMATICS · CORE LANGUAGE
A function assigns each allowed input exactly one output. Functions are the language of change, dependence and mathematical models — connecting algebra, geometry, calculus, probability and beyond.
THE FOUR QUESTIONS
Which input values are allowed? Restrictions can come from denominators, roots, logarithms or the model itself.
Which output values can the function actually produce?
Intercepts, symmetry, growth, turning points and asymptotic behaviour reveal structure visually.
Shift, scale, reflect and combine functions without losing track of what changes.
Inverse functions reverse input and output when the original function is one-to-one on the chosen domain.
Composition feeds the output of one function into another and builds more complex models.
FUNCTION LIBRARY
Definition, domain, codomain, range, notation and common families.
Start with functions →f(x)+aTranslations, stretches, compressions and reflections of graphs.
Explore transformations →f⁻¹Composition, invertibility and how to recover an input from an output.
Explore inverses →maxLocal and global maxima and minima, with links toward calculus.
Explore extrema →mx+bSee how straight-line graphs connect directly to linear equations.
Connect to linear equations →x²Parabolas, zeros, discriminants and quadratic equations.
Connect to quadratics →WHY FUNCTIONS MATTER
Equations ask where expressions are equal. Functions describe entire relationships. Calculus then studies how those relationships change — through limits, derivatives and integrals.