Introduction Edexcel Higher

Introduction to functions

What is a function?

• A function is a combination of one or more mathematical operations that takes a set of numbers and changes them into another set of numbers

• The numbers being put into the function are often called the inputs

• The numbers coming out of the function are often called the outputs

• A function may be thought of as a mathematical “machine”

  • For example, for the function “double the number and add 1”, the two mathematical operations are “multiply by 2 (×2)” and “add 1 (+1)”

    • Putting 3 in to the function would give 2 × 3 + 1 = 7

    • Putting -4 in would give 2 × (-4) + 1 = -7 

    • Putting in would give

What is function notation?

• A function, f, with input can be written as

  • Letters other than f can be used

    • The letters g, h and j are common but any letter can be used

    • Typically, a new letter will be used to define a new function in a question

• For example, the function with the rule “triple the number and subtract 4” would be written

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