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ExamsLogic Revision Series | Independent study guide based on the official curriculum.
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Higher Level Mathematics Revision Notes

Topic 5.1: Functions

These notes teach Functions clearly in simple English and then take it further with the higher-level material. The aim is to build understanding first and exam confidence second.

Curriculum Irish Leaving Certificate
Subject Mathematics
Level Higher Level
Premium feature Teacher-style explanations and cleaner study flow
Focus
Understanding before memorising
Interactive
Study tools and guided structure
Question Style
Explained examples and exam practice
Format
Website reading and printable notes

Subtopics Covered

  • What is a Function?
  • Key Function Types
  • 📝 Exam Style Questions

What Makes This Version Better

  • Simple explanations first, then deeper higher-level extension
  • Clearer student-friendly language across the topic
  • Worked examples unpacked in steps
  • Interactive study tools where they genuinely help
  • SEO-friendly website naming and branding
Disclaimer This publication is an independent educational resource developed by ExamsLogic and compiled by experienced educators. It is based on publicly available official curricula, including Cambridge, Pearson Edexcel, IB, and the Irish Leaving Certificate. This product is not endorsed by, affiliated with, or sponsored by any examination board or governing authority. All registered trademarks remain the property of their respective owners.

Learning Objectives

What You Should Be Able To Do

    Interactive Study Tools

    These tools are here to help students slow down and think about the method before rushing to an answer.

    Tool 1

    Study Planner

    Use this to break a topic into small study sessions.

    Plan: A clear breakdown will appear here.
    Tool 2

    Method Reminder

    This quick guide reminds students what to do when they feel stuck.

    • Read the story: what is the question really asking?
    • Choose the method: identify the correct idea before calculating.
    • Show the reason: do not skip the logic.
    • Check the answer: make sure it fits the situation.

    1. What is a Function?

    Simple explanation: This section explains how one value can depend on another, and how to read that relationship carefully.

    A function is a rule that assigns each input (Domain) to exactly one output (Range).

    • Domain: The set of all possible input values (x).
    • Range: The set of all resulting output values (f(x)).

    2. Key Function Types

    Simple explanation: This section explains how one value can depend on another, and how to read that relationship carefully.
    • Linear: f(x) = mx + c (A straight line).
    • Quadratic: f(x) = ax² + bx + c (A parabola).
    • Composite Functions: f(g(x)) — performing one function *after* another.
    • Inverse Functions: f⁻¹(x) — the "undo" operation that swaps the domain and range.
    Examiner Tip
    💡 Examiner Tip: To find the inverse function f⁻¹(x): 1. Replace f(x) with y. 2. Swap the x and y variables. 3. Rearrange the formula to solve for y.

    📝 Exam Style Questions

    Simple explanation: This section explains how one value can depend on another, and how to read that relationship carefully.

    Easy Q1: If f(x) = 2x + 3, find f(5).

    Medium Q2: Find the inverse of f(x) = x + 4.

    A1: f(5) = 2(5) + 3 = 13.

    A2: y = x + 4. Swap: x = y + 4. So y = x - 4. f⁻¹(x) = x - 4.