Math Dictionary / Function
Function
A function is a rule that gives exactly one output for each input.
FunctionsGrade 8Algebra 1Algebra 2SATACT
What it means
If you put in one x-value, a function gives back one y-value.
Also called: input-output rule
Examples
| f(x) = 2x + 1 |
| Input 3 gives output 7 in f(x) = 2x + 1 |
| A vertical line test checks graphs |
Common mistake
One input cannot have two different outputs in a function.
Try one
Question: For f(x) = x + 4, what is f(6)?
Show answer
f(6) = 6 + 4 = 10.