math / Algebra & Functions / free

Functions

A function is a rule for turning one quantity into another.

Follow the mechanism1 / 3

An input is selected. The domain says which values are allowed to enter the rule.

function machineone input → one output

Choose a rule

input x1.5

→

rulef(x) = 2x + 1

→

output f(x)4.0

Change the input x = 1.5

Compare a second inputx₂ = -1.5

Same rule, different inputs: f(1.5) = 4.0 and f(-1.5) = -2.0. The rule stays fixed while the input changes.

Try a sample

Choose a rule and send an input through it.

A function assigns exactly one output to each allowed input. Change the rule, then test how the same input behaves under a different relationship.