Functions

📘 What Is It?

A function is a rule that connects every input to exactly one output.
Think of it like a machine: you put in a number (input), and the machine gives one number back (output).

🔑 Clue to Remember

One input → One output
Never two answers for the same question!

📌 Example

If the rule is “multiply by 2,” then:

• Input: 3 → Output: 6
  
  

• Input: 5 → Output: 10
  
  

🎯 Why It Matters

Functions help us understand how quantities are related and are used in graphs, programming, and real-life math models.