I'm SOOO CONFUSED!!

How do I determine an equation is a function or not by looking at an equation

example:
x^2 +2y=3
I tried to slove this equation by getting y by its self but I don't know what to do with the answer! I need help I have an exam tomorrow!

If you solve for equation for y, you get:



This is a quadratic, more specifically, a concave down parabola.

An equation is not a function if one unique input can get you 2 or more different outputs.

For instance,
. This is not a function because if x=9, then y can equal 3 or -3.

Is your parabola a function?

There's lots of info on the net if you Google.