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This topic covers function notation f(x), evaluating and substituting into functions, forming composite functions fg(x) and finding inverse functions. It's examined right across GCSE and iGCSE Maths. Learn it free on eClassroom through guided worked examples and instantly-marked exam-style questions.
How you do it
f(x) means substitute the value in place of x. For a composite like fg(x), do g first and feed the result into f. To find the inverse, write y equals f(x), swap x and y, and rearrange.
Before you start
The prerequisite is substitution and algebraic notation. It sets up composite and inverse functions at A-Level. It appears at Higher tier.
What you learn
A function is a rule that turns an input into an output, written f(x). We can evaluate f at a value, combine two functions into a composite function, and reverse a function with its inverse. A composite function applies one function then another. To find it, write y = f(x), swap the roles of x and y, then rearrange to make y the subject. The course works through function notation, composite functions and inverse functions. Every section has instant-feedback practice questions matched to Edexcel iGCSE 4MA1 and the other major GCSE boards, and the course finishes with full exam-style questions you mark yourself.
Related Topics
Functions is a Algebra topic in the GCSE syllabus, covered here at Higher tier. You work through 3 concepts and 2 worked examples, testing yourself at 3 points. Nearby topics in the same strand are Gradients & Rates of Change, Inequalities, Linear Equations and Linear Graphs. The Algebra revision engine gives you as many extra questions as you want, tracked on your skill tree.
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