Mathematics - Functions - Introduction - Understanding functions - What Is a Function?

7 steps: (1) A function is a relationship where each INPUT has exactly ONE OUTPUT. (2) The set of all inputs = DOMAIN. The set of all outputs = RANGE. (3) Think of it as a rule: 'For every x, there's exactly one y.' (4) Table representation: x|1,2,3,4 → y|3,5,7,9. Each x has one y. ✓ Function. (5) G