Question

Can someone help me please? I need to find which of these is a function and I have no clue which is the answer.

Answer 1

Only the fourth example is a function.

Explanation:

What you need to look at is whether there are any values of the independent variable `x` which map onto more than one dependent variable `y`. To be a function there can not be any duplication,

In the first example
`color(white)("XXX")3` is mapped onto both `-5` and `0`
So it is not a function.

In the second example
`color(white)("XXX")-1` is mapped onto both `-11` and `5`
So it is not a function.

In the third example
`color(white)("XXX")3` is mapped onto both `14` and `19`
So it is not a function.

In the fourth example
`color(white)("XXX")`There is no place where two points (values of `y`)
`color(white)("XXX")`are identified (mapped from) any value of `x`
So it is a function.