Question

Does the table represent a function? Why or why not?

х-у
2-4
3-5
3-6
4-7
5- 7
A. No, because there are two y-values that are the same.
B. No, because one x-value corresponds to two different y-values.
C. Yes, because there are two x-values that are the same.
D. Yes, because every x-value corresponds to exactly one y value.

Answer 1

Answer: Choice B.

No, because one x-value corresponds to two different y-values.

Specifically we have x = 3 map to both y = 5 and y = 6 at the same time. A function is only possible when each x value goes to one y value only.

A handy trick is to look at the list of x coordinates. If any x coordinates repeat themselves, then we likely won't have a function.

The y values can repeat, but the function won't be one-to-one.

Use of the vertical line test is a visual way to check if we have a function or not.