Question

Im a little confused. Please Help?

Determine whether the formula describes y as a function of x. Explain your reasoning.

y = -x

Answer 1

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
|
|

Answer 2

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

Answer 3

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

Answer 4

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

Answer 5

@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!

Answer 6

http://www.youtube.com/watch?v=JkziIA3AtMM

Answer 7

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

Answer 8

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

Answer 9

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.

Answer 10

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

Answer 11

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

Answer 12

oh really? yay! that's great! glad it made sense! :D