Functions Toolkit (OCR GCSE Maths)

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
  
  • It may be thought of as a mathematical “machine”
  • For example, if the function (rule) is “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 x would give 2x + 1
• The number being put into the function is often called the input
• The number coming out of the function is often called the output
• A function can be shown in a diagram form
  • 
    • The input is x and the output is y
    • In algebra, this says 5x + 6 = y