Question

G = {(1, 1), (1, 2), (1, 3), (1, 4)} Is G a function and why?

Answer 1

`G` is not function. The reason is that it is not one-to-one.

Explanation:

A function is a mapping that is also one-to-one.

`G` is indeed a mapping; it takes an input and relates it to one or more outputs.

• Input:
  `1`, output:
• Input:
  `1`, output:
  `2`.
• Input:
  `1`, output:
  `3`.
• Input:
  `1`, output:
  `4`.

A mapping is one-to-one if and only if each input is mapped to only one output.
`G` is not one-to-one because it maps the input
`1` to four different outputs. Hence,
`G` isn't a function.