Answer:
−4y
Step-by-step explanation:
Since the directrix is vertical, use the equation of a parabola that opens up or down.
(x−h)2=4p(y−k)
Find the vertex.
The vertex (h, k) is halfway between the directrix and focus. Find the y coordinate of the vertex using the formula y = y coordinate of focus + directrix 2. The x coordinate will be the same as the x coordinate of the focus.
(3,−1+1
___
2)
Simplify the vertex.
Add − 1 and 1. (3,0/2) Divide 0 by 2. (3,0).
Find the distance from the focus to the vertex.
The distance from the focus to the vertex and from the vertex to the directrix is | p |. Subtract the y coordinate of the vertex from the y coordinate of the focus to find p. p = − 1 − 0 Subtract 0 from − 1 . p = − 1.
Substitute in the known values for the variables into the equation ( x − h ) 2 = 4 p (y − k). (x − 3) 2 = 4 (− 1) (y − 0).
Simplify.
(x − 3) 2= −4y
= −4y
