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Of course it's a function!
If it passes the vertical line test, it's a function.
Vertical line test?
I checked the answer key, and it's not a function..
Have you checked the definition of a "function"?
What does does it say?
A function is a special relationship between values: Each of its input values gives back exactly one output value.
Set up a table of values like ...-3, -2, -1, 0, 1, 2, 3, .. and test it.
How does that let me know whether it's a function or not?
lol, it's just a question
Does each input value give "back exactly one output value."???
Oh, I understand now! Thanks :)
But, won't I have to try out all of the numbers? What if somewhere along the line, the x has more than one y value?
are you sure you haven't entered the equation incorrectly perhaps it should be \[x= y^2 + 4\]
No, that is incorrect. The y value is always the output.
omg it's just a correctionnn
no its a graph that looks like |dw:1359706698575:dw|
Well, that's the reflection of y=x^2+4 over the y axis, but no that's not correct. I have the answer key
Once you try a few input values you will be able to draw a "graph" like above...
Wait @campbell_st how did you get that graph?
It the graph of \[x = y^2 + 4\] which isn't a function and that's why I asked if you had typed in the correct equation. Because the equation you have entered for the question is definitely a function...
Oh yes! Yes, that is what I meant. I have a question for you!
Once you try a few input values you will be able to draw a "graph" of the output values.
how do you get function for this line? |dw:1359707035624:dw|
*how do you get the function for this line
Like, how did you know it was x=y^2+4?
yep... so as @abb0t said... if you use a vertical line you can see it cuts the curve twice... so its not a function... if the vertical like only cuts once you have a function...
For all we know, couldn't it have been y=(x+4)^2
because you said that the answer was... not a function.. which to me you have transposed the x and y.... just an experience thing
The vertical line test made it so much easier! So @abb0t was correct in the first place :P
and any parabola with x as the independent variable will be a function..
yes he was...
Thank you :) You made it clear for me
glad to help
Or the answer key is wrong...the important thing is to know to use the definition: A function is a special relationship between values: Each of its input values gives back exactly one output value.