Question

Which relation is a function?
x −2 −2 0 1 8
y 3 6 0 0 9


B.
x 3 5 7 14 14
y −9 5 −9 1 2


C.
x −3 4 5 9 12
y 1 −2 −2 0 7


D.
x −7 −5 6 8 8
y −3 8 1 1 −9

Answer 1

WHALECOME TO OPENSTUDY!!

Answer 2

Let y=f(x).
Ask yourself if you are able to give the value of f(x) for every x.
For example, if I have
x 2 3 5 5
y 1 2 3 4
Then f(2)=1, f(3)=2, but f(5)=3 or f(5)=4? Since we cannot answer the question, the relation is NOT a function.
Another example:
x 2 3 5 5
y 1 2 1 1
Here, we know that f(2)=1, f(3)=2, and f(5)=1 with no ambiguity, so it is a function.

Answer 3

@mathmate so B?

Answer 4

Are you able to tell without ambiguity what is f(14)? If not, it is not a function.

Answer 5

another trick to distinguish functions from non functions, answer the question
"does an x value repeat with different y values? "
If an x value does repeat with different y values, then its not a function

Answer 6

no @mathmate

Answer 7

So you have to look for another choice which answers yes to all the possible values of x.

Answer 8

so the answer is B?

Answer 9

Yes.

You may have found that whenever there is no repetition in x, it would be a function.
When there is repetition, you will need to ask yourself the question above for the repeated values.

Answer 10

ok thanks

Answer 11

You're welcome! :)