# Algebra

posted by .

Can someone tell me if I am right?

I need to find the equation of a parabola. I am not sure if this is the correct way or if I have the correct answer.

Vertex at origin, focus is at (0,3)

Equation of parabola
vertex (0,0) focus (0,3)
focus (h,k+p)
(0,0+3)
y=0-3
directrix y=-3
a=(1/4)(p)
a=(1/4(-3))=(-1/12)
a=(-1/12) h=0 k=0
y=(-1/12)(x-0)^2+0

• Algebra -

shouldn't your parabola open upwards ?
your -1/12x^2.... makes it open down.

I do it this way:
let P(x,y) be any point on the parabola
by definition, the distance from P to the focal point is equal to the distance to the directrix --->
√(x^2 + (y-3)^2) = √(y+3)^2)

square both sides, and simplify to get

y = (1/12)x^2

## Similar Questions

1. ### Math

y^2=8(x-3) how would you get the coordinates. vertex = 3,0 then what?
2. ### Albebra

Find the vertex of the function y = –x2 + 2x + 8. It is where the derivative -2x + 2 = 0. Since you probably haven't learned about derivatives, do it this way: Rewrite is as -x^2 +2x +8 = -(x-1)^2 + 7 Now look at the form of the …
3. ### Algebra

I'm trying this again, I'd like the quadratic form, so i can then work the intercepts myself. SO: what's the quadratic form of 1/4(x+3)^2-4 I need it to find the intercepts of the parabola it describes. Check: I think the parabola …
4. ### algebra problem

I need to find the equation of a parabola. I am not sure if this is the correct way or if I have the correct answer. Vertex at origin, focus is at (0,3) Equation of parabola vertex (0,0) focus (0,3) focus (h,k+p) (0,0+3) y=0-3 directrix …
5. ### algebra

6. Find the equation of each parabola described below. a) parabola with vertex (0,0) and the focus (0,7) b) parabola with focus (-3,0) and directrix x=3 c) parabola with vertex (3,3) and directrix x=-1 d) parabola with focus (-2,-1) …
6. ### Algebra II

In this set of eight problems, we have to match each equation with the correct description of its graph. However, these are test corrections I'm doing and I do not have the previous multiple choice answers so I can deduct from it, …
7. ### Algebra

I have a parabola that I have to write as an equation I found the vertex as (-3,-2) and the following points (-4,-1)(-2,-1),(-5,2),(-1,2). I can't seem to come up with the correct equation. I'm using the formula y=a(h-k)^2+k but I'm …
8. ### Algebra 1 parabola's

I have a graph with a parabola on it and asked to write the function for f(x) in standard form. I know that standard is y=ax^2+bx+c obviously, since the points are on the graph we know x and y so a,b and c need to be found. The vertex …
9. ### Algebra

An engineer designs a satellite dish with a parabolic cross section. The dish is 14 ft wide at the​ opening, and the focus is placed 4 ft from the vertex. ​a) Position a coordinate system with the origin at the vertex and the​ …
10. ### Algebra

An engineer designs a satellite dish with a parabolic cross section. The dish is 10 ft wide at the​ opening, and the focus is placed 8 ft from the vertex. ​a) Position a coordinate system with the origin at the vertex and the​ …

More Similar Questions