(y+1)^2-3=2x

is this a function? :S

Question

(y+1)^2-3=2x

is this a function? :S

hero · Answer

In order for an equation to be a function, it has to pass the vertical line test. 

Let's solve for y and see what happens.

anonymous · Answer

@bmp i haven't even gotten to that part of the question yet. lol right now it's just asking me if its a function

hero · Answer

(y+1)^2 - 3 = 2x
(y+1)^2 = 2x + 3
y+1 = + or - sqrt(2x+3)
y = + or - sqrt(2x+3) -1

Since this does not pass the vertical line test, it is not a function.

anonymous · Answer

I didn't mean that. I wrote it poorly. What I meant is that there aren't defined sets to a rule, i.e., a function is something like f:A->B, a rule that takes values in set A and have their reciprocal at set B. Generally, we write f:R->R for a real function.
But Hero's answer is better than mine.

anonymous · Answer

@hero how does it not pass the vertical line test? isn't this a square root function??

hero · Answer

I don't like writing the + or - part because it makes it appear as if either one part or the other part can be used when in actuality, you have to graph both the positive and negative x, then perform the vertical line test. It looks something like this when graphed: 

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