Functions

Not a function: (1, 3) and (1, 5). Input 1 has two outputs, so the machine wouldn't know what to give.
Still a function: (1, 3) and (2, 3). Two inputs can share the same output.
On a graph: use the vertical line test. If any vertical line hits the graph more than once, it's not a function.
In a mapping diagram: look for one input with two arrows coming out of it.

with the Function Machine

x values go in, y values come out. Feed the machine, read domain and range, name the parent functions, and slide graphs into place.

Stretch your knowledge

Ready for more? These use the rest of the parent functions: cubic, square root, rational 1/x, exponential, logarithmic and greatest integer.