Which coordinates does not represent a function?

Set 1

Step-by-step explanation:

To have a function, you cannot have the same x-coordinate more than once.

In sets 2, 3, and 4, all x-coordinates of each set are different, so they are functions.

In set 1, the x-coordinate 1 appears twice, so set 1 is not a function.

i'm not sure i quite understand, could you provide more information?

step-by-step explanation:

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