Functions · Ordinary Level
Functions
Ordinary Level · From your notes · Tap NEXT to begin
Section 2 of 6
Domain, Range & Arrow Diagrams
Three short words
Domain = set of inputs. Range = set of outputs you actually get. Codomain = the bigger set the outputs live in. The range is always inside the codomain.
An arrow diagram is the picture of a function: two ovals, inputs on the left, outputs on the right, an arrow from each input to the value the rule sends it to.
The range lists each output once — a set has no repeats. Two arrows can land on the same output; that’s fine.
Is it a function?
Every input is used, and each input is used only once. Every input must have exactly one arrow leaving it. Outputs may repeat or go unused — only the inputs must behave.
Two arrows leaving one input → not a function. An input with no arrow leaving it → not a function (an input left unused).
Part 2 done.
Next up: Solving with Functions. Head back to the hub for the next part.