Question

The table below does not represent a function why? ​

Answer 1

Because X (10) repeats

Explanation:

A function has no repeated X but here in your x variable 10 is there twice so therefore it is NOT a function

You can use the pencil test also in a graph, align your pencil vertically and see if there are multiple points that have the same X and if there isn't any repeated its a function.

Answer 2

The function is a relation between two sets that associates to each element of the first set exactly one element of the second set.

We have x = 10 twice with different f(x) associated, 5 and 20.

If we plot those points they will be on same vertical line, thus the vertical line test is failed.