Worksheet for reviewing relations and functions, including examples and exercises on ordered pairs, mappings, tables, and graphs.

Final Answer:
A function is where a relation has only one y-value for every x-value.

Ordered pairs {(2, 1), (3, 2), (4, 1), (−2, 0)}:
- X-values: 2, 3, 4, −2 → none repeated
- ✔ Yes, it is a function.

Mappings (left: −2, −1, −2 → right: 9, 1, 2, 1):
- X = −2 maps to both 9 and 1 → x-value repeated with different y-values
- ✘ Not a function.

Table (X: −2, −1, 5, 1, 0; Y: all −1):
- X-values are all different
- ✔ Yes, it is a function.

Graph (circle centered at origin):
- Vertical line test: a vertical line through the center hits the graph twice
- ✘ Does not pass vertical line test → not a function.