## DaniBieber 3 years ago Im a little confused. Please Help? Determine whether the formula describes y as a function of x. Explain your reasoning. y = -x

1. joshi

well a function is a relation between numbers where every x value has only one corresponding y value. for ex: if i have a set of numbers (2,1) (2,0) this isn't a function because for the x value of 2 i have 2 different y values of 1 and 0. so for this question you can start by making a table of values to see if it's a function or not. ex: X | Y ------ 1| -1 | |

2. DaniBieber

@joshi Thank you, but i'm still confused. I don' have a set of numbers..

3. Decart

plug in and solve like x=2 y=-2

4. joshi

oh i'm sorry i was just trying to a explain what a function was with an example. at the end i was saying that you could make a chart/table to see if it was a function or not. like up there i said if x is 1, then y is -1. because y= -x so y= -(1) , y =-1 and if x was 2, y would be... etc. if the function thing or the definition is confusing, it's basically like: (the photo) kinda lame but that's how i take notes

5. DaniBieber

@Decart @joshi thank you guys so much for your help,and your notes, they helped a lot, but i'm still confused. So y is a function of x in this equation, right? In y=-x? But, why. Once, i figure that out I will see how you guys actually did it, and i will be a whole lot confused!

6. Decart
7. joshi

yes it's a function. well why do you think it is?

8. DaniBieber

@joshi because when you make a table, there is no x and y value that are equal to eachother?

9. joshi

it's not about the x and y values being equal to each other. it's like one x value can't have 2 different y values.

10. joshi

so in the photo each x value has a certain y value. but when x is 5 y is 7. and then when x is 5 y is also 8. so its not a function because for the same x value you have 2 different y values

11. DaniBieber

@joshi that makes so much sense! thank you so much. I get it now!

12. joshi