# Recognizing functions

10 videos

2 skills

Relationships can be any association between sets of numbers while functions have only one output for a given input. This tutorial works through a bunch of examples of testing whether something is a valid function. As always, we really encourage you to pause the videos and try the problems before Sal does!
Common Core Standard: 8.F.A.1

### How to check if a set of points on the graph represents a function (example)

VIDEO
4:07 minutes

Sal checks whether a given set of points can represent a function. For the set to represent a function, each domain element must have one corresponding range element at most.

### How to check if a table represents a function (example)

VIDEO
4:40 minutes

Sal checks whether a table of people and their heights can represent a function that assigns a height to a name.

### How to check if a relationship between variables described verbally represents a function (example)

VIDEO
1:31 minutes

Sal checks whether y can be described as a function of x if y is always three more than twice x.

### Does a vertical line represent a function?

VIDEO
1:40 minutes

Sal explains why a vertical line *doesn't* represent a function.

### Recognizing functions (example 3)

VIDEO
1:16 minutes

### Recognizing functions (example 4)

VIDEO
3:33 minutes

### Recognize functions from tables

PRACTICE PROBLEMS

Determine whether a table of values of a relationship represents a function.

### How to check if a relationship between real-world quantities described verbally represents a function (example)

VIDEO
3:23 minutes

Sal checks whether a description of the price of an order can be represented as a function of the shipping cost.

### Functions as graphs

VIDEO
9:35 minutes

### Recognize functions from graphs

PRACTICE PROBLEMS

Determine whether a given graph represents a function.