Question

I need some help with this. http://screencast.com/t/X8uEL5Bh9E
Tell me what you think.

Answer 1

The general form is y = a(x - h)^2 + k

Answer 2

isn't the general form of this (x-h)^2=4p(y-k)

Answer 3

vertex = (0,3 ) focus =(4,3)

Answer 4

focus = (h+p,k)

Answer 5

or you can do by directrix h-p=-4

Answer 6

Whoa whoa, wait. How did you get those?

Answer 7

from the picture?

Answer 8

Right, I know. But the whole focus and directrix thing confuses me. The focus and directrix are supposed to be the same distance away from the vertex, right?

Answer 9

your directrix is going to be h-p,k or h,k-y

Answer 10

indeed they are

Answer 11

they are both p distance away from your vertice

Answer 12

And you found the vertex just by looking at the picture?

Answer 13

indeed

Answer 14

because your focus and directrix will always be symetrical with your vertex

Answer 15

And since the second part of the question asks me to explain how I got my answer, would I say "By just looking at the graph"?

Answer 16

well if you find the what p is

Answer 17

you can find the point of hte vertex

Answer 18

does it give any information on what a is?

Answer 19

And p is the distance from the focus to the vertex? I'm sorry for being so slow. And yes, it does, but it's a rather long explanation. Let me see if I can show you a picture of what it is.

Answer 20

Here. Tell me if this answers your question. http://screencast.com/t/yp4uNcUhy

Answer 21

Outkast?

Answer 22

hold on i'm trying to figure out why my books contradict eahc other with standard and general forms

Answer 23

Oh, okay.

Answer 24

Your books might have a different general form than my books, but for this purpose, can we use my form?

Answer 25

well do you need explanation for h, k?

Answer 26

Alright, THIS should really help you. http://screencast.com/t/eKwUrcfLmG
And no, I'm pretty sure I got that. It's just the focus/directrix thing that trips me up.

Answer 27

The video will help you with 'a' and I guess the other stuff too.

Answer 28

yes well i know that but as far as i know the only way you can infer is by knowing the vertex = 0,3

Answer 29

Infer what? a?

Answer 30

that the vertex = (0,3) once you find that you can find c/p which is your distance between your focus and your vertex

Answer 31

So what is the general form for it? I'm stuck at x = a(y - 3)^2

Answer 32

I can't figure out a.

Answer 33

a will be 1/4c/p which will be 1/4*4

Answer 34

a is going equal 1/4c

Answer 35

where c is your distance from focus to vertext

Answer 36

So, a = 1/16?

Answer 37

i believe so

Answer 38

so x = 1/16(y - 3)^2 is my final answer?

Answer 39

yes

Answer 40

Whew. I sure hope so. I'm just too tired to check it any further though. It's 3 in the morning over here. Thank you so much for your help though. You were fantastic.

Answer 41

you can check that with like saifoo because i haven't done anything like this in about 6 years. I use standard form much more often

Answer 42

Is saifoo still on?

Answer 43

i believe he is

Answer 44

just post like CHECK: blah blah blah and he'll probably seei t

Answer 45

I sent him a message in the chat box, so let's see if he reads it.