Answer:
the first is a function and the parabola is not a function
Explanation:
A simple way to know why is the vertical line test.
Draw a vertical line and see whether if there are more than one point in the vertical line. If there's more than one point in the line then it's not a function, but if only one point on the vertical line it IS a function.
In the first graph, you'll notice that any vertical line you'll draw won't pass through two points ever. On the other hand, second graph will have two points found in the vertical line drawn by you, for example: (-2, 3);(-2, -3)
Wish you've enjoyed my answer because the more you enjoy maths, taste it, love it, and understand it, the more you will be successful in it. Good luck