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sakigirl
 3 years ago
Is y=x^2+4 a function? How do you know?
sakigirl
 3 years ago
Is y=x^2+4 a function? How do you know?

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abb0t
 3 years ago
Best ResponseYou've already chosen the best response.1Of course it's a function!

abb0t
 3 years ago
Best ResponseYou've already chosen the best response.1If it passes the vertical line test, it's a function.

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0I checked the answer key, and it's not a function..

skullpatrol
 3 years ago
Best ResponseYou've already chosen the best response.1Have you checked the definition of a "function"?

skullpatrol
 3 years ago
Best ResponseYou've already chosen the best response.1What does does it say?

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0A function is a special relationship between values: Each of its input values gives back exactly one output value.

skullpatrol
 3 years ago
Best ResponseYou've already chosen the best response.1Set up a table of values like ...3, 2, 1, 0, 1, 2, 3, .. and test it.

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0How does that let me know whether it's a function or not?

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0lol, it's just a question

skullpatrol
 3 years ago
Best ResponseYou've already chosen the best response.1Does each input value give "back exactly one output value."???

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0Oh, I understand now! Thanks :)

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0But, 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?

campbell_st
 3 years ago
Best ResponseYou've already chosen the best response.1are you sure you haven't entered the equation incorrectly perhaps it should be \[x= y^2 + 4\]

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0No, that is incorrect. The y value is always the output.

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0omg it's just a correctionnn

campbell_st
 3 years ago
Best ResponseYou've already chosen the best response.1no its a graph that looks like dw:1359706698575:dw

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0Well, that's the reflection of y=x^2+4 over the y axis, but no that's not correct. I have the answer key

skullpatrol
 3 years ago
Best ResponseYou've already chosen the best response.1Once you try a few input values you will be able to draw a "graph" like above...

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0Wait @campbell_st how did you get that graph?

campbell_st
 3 years ago
Best ResponseYou've already chosen the best response.1It 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...

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0Oh yes! Yes, that is what I meant. I have a question for you!

skullpatrol
 3 years ago
Best ResponseYou've already chosen the best response.1Once you try a few input values you will be able to draw a "graph" of the output values.

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0how do you get function for this line? dw:1359707035624:dw

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0*how do you get the function for this line

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0Like, how did you know it was x=y^2+4?

campbell_st
 3 years ago
Best ResponseYou've already chosen the best response.1yep... 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...

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0For all we know, couldn't it have been y=(x+4)^2

campbell_st
 3 years ago
Best ResponseYou've already chosen the best response.1because you said that the answer was... not a function.. which to me you have transposed the x and y.... just an experience thing

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0The vertical line test made it so much easier! So @abb0t was correct in the first place :P

campbell_st
 3 years ago
Best ResponseYou've already chosen the best response.1and any parabola with x as the independent variable will be a function..

sakigirl
 3 years ago
Best ResponseYou've already chosen the best response.0Thank you :) You made it clear for me

skullpatrol
 3 years ago
Best ResponseYou've already chosen the best response.1Or 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.
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