Answer: No, it is not a function
Why not? Because of the two points (-1,-4) and (-1,2)
The x values are repeating here. The input x = -1 leads to more than one output (y = -4 and y = 2 at the same time). A function is where all the inputs lead to only one output.
Visually if you plotted all four points, you will see it is possible to draw a vertical line through two of the points, those two points I mentioned earlier. This tells the reader that the relation fails the vertical line test and it shows it is not a function.
