Read over these next few slides to review our lesson on Functions!

Function or Relation (Not a Function?)

Time to practice!

Relation (NOT A FUNCTION)

The left column is the inputs (x-values). -2 repeats two times, so this is not a function.

Is this a function?

{ (4, 4) (2, 2) (5, 5) (8, 8) }

YES, THIS IS A FUNCTION!

The x-values are 4, 2, 5, and 8. None of them repeat!

Is this a function?

{ (-1, 0) (7, 4) (-5, 2) (-1, 5) }

NO, THIS IS NOT A FUNCTION!

The x-values are -1, 7, and -5. The value -1 repeats two times, so this is not a function.

NO, THIS IS NOT A FUNCTION

The input (x-value) 4 has two arrows pointing away from it. It has more than one output.

YES, THIS IS A FUNCTION

Even though all the inputs go to the same output, each input only has ONE ARROW going away from it.

YES, THIS IS A FUNCTION

It passes the vertical line test. Each vertical line only touches the graph once.

NO, THIS IS NOT A FUNCTION

It does not pass the vertical line test. The graph touches one vertical line in two different places.

NO, IT IS NOT A FUNCTION

Two points are on the same vertical line (fails the vertical line test).