3 5/15 is not larger than 3.3385
Check the picture below.
so the focus point is at 5, -1 and the directrix is above it, meaning is a vertical parabola, and is opening downwards, like in the picture.
keep in mind that the vertex is half-way between those two fellows, at a "p" distance from either, in this case 1 unit, since the parabola is opening downwards, "p" is negative then, or -1, and the vertex will be from 5, -1 up one unit, so 5,0.
Yes it’s correct. You just need to plug each of the x and y values to see if they satisfy the equation.