Question

more parabolas! ∩◕㉨◕∩

Answer 1

Find the standard form of the equation of the parabola with a focus at (3, 0) and a directrix at x = -3.

Answer 2

Use that formula I gave you

Answer 3

I use that formula because it can be applied to any parabola as long as you have the focus and directrix

Answer 4

i know .-. i lost it so im looking for it :p

Answer 5

\[\sqrt{(x - x_1)^2 + (y - y_1)^2} = \sqrt{(x - x_2)^2 + (y - y_2)^2}\]


Plug the points for the focus on the left side and the point for the directrix on the right side:


focus = (3,0)
directrix = (-3, y)

Answer 6

Watch your signs :)

Answer 7

hmmm

Answer 8

do you know what it looks like? if so you can do find the equation without much trouble

Answer 9

lol i guess you learned that one the hard way c:
okay so sqrt (x-3)^2+(y-0)^2 + sqrt (x-(-3))^2+(y-y)^2

Answer 10

all you need is the vertex, and the distance from the vertex to the focus

Answer 11

okayyyy so x^2 -6x+9 +y^2 +x^2 +6x+9 +y^2-y^2

Answer 12

Where's the equal sign?

Answer 13

amongst other errors

Answer 14

no,i need an answer with 12 in it satellite. and oh :c fine then
x^2 -6x+9 +y^2 = x^2 +6x+9 +y^2-y^2

Answer 15

@Hero what is wrong with
\[4p(x-h)=(y-k)^2\]?

Answer 16

woah whats the p?

Answer 17

I've never seen that before ever

Answer 18

you can see from your eyeballs that the vertex is \((0,0)\) and \(p\) is the distance from the vertex to the focus

Answer 19

which is evidently \(3\)

Answer 20

reason 1 of why i hate math..... there are 20 formulas for one problem ._.

Answer 21

then you are done
since it opens to the right, and the vertex is \((0,0)\) is it
\[4\times 3(x-0)=(y-0)^2\] or just
\[12x=y^2\]

Answer 22

nice worked out examples here
http://www.purplemath.com/modules/parabola.htm

Answer 23

Yeah, I get you at @satellite73 but I think people tend to use what they are used to and I think both methods are equally easy.

Answer 24

not to argue with @Hero but you do not need the distance formula to find the distance between \((0,0)\) and\((3,0)\)

Answer 25

they are on the same horizontal axis
it is just 3

Answer 26

but you got wrong answer .-. thus your way is wrong

Answer 27

@lovelyharmonics, you should re-check your work more carefully.

Answer 28

no, actually i got the right answer
it opens to the right, not the left

Answer 29

tell that to my answer choices, none of which are 12x=y^2

Answer 30

we can check it if you like
http://www.wolframalpha.com/input/?i=parabola+12x%3Dy^2

Answer 31

is one of them
\[x=\frac{1}{12}y^2\]? that is the same

Answer 32

x^2 -6x+9 +y^2 = x^2 +6x+9 +(y - y)^2

-6x + y^2 + 6x

y^2 = 6x + 6x

y^2 = 12x

\(\dfrac{y^2}{12}= x\)

Answer 33

yeah ^.^ so you just divided those both by 12 right?

Answer 34

you both derserve medals c: thus hero you give satilite one and ill give you one okay? c:

Answer 35

@satellite73 earns his medals just for showing up

Answer 36

.-. what? you cant do that....

Answer 37

No only @satellite73 can earn his medals that way. He's earned it

Answer 38

If you haven't noticed, he's the on site guru here

Answer 39

i spent most of them, but i have enough anyways thanks

Answer 40

Yeah, I notice we can't redeem these medals for anything