have a vertex at (-4,-1) with a vertical axis of symennetry. which one has a directrix of y=-4
so far i got (x+4)^2=?(y+1)
what is the ?..?!! how do i get that
Hello peekybooyouYou're right so far. You have used the fact that the parabola has vertex at and a vertical axis of symmetry. You've replaced by and by to give a parabola whose vertex is at .
Now you need to use the fact that the parabola has directrix .
If in the coordinates, the directrix is , in the coordinates it is
So in coordinates the equation is ; in coordinates it is
Grandad