Answer: No, it is not a function
If you can draw a vertical line through more than one point on the curve, then it's not a function. In this case, we can draw such a line. The graph is said to have failed the vertical line test.
What this means is that some x inputs lead to more than one y outputs. A function is only possible if any x input leads to exactly one y output. The x input must be in the domain.
