Question

x^2+8y=0 find the vertex focus and directrix

Answer 1

All of these are straight formula vertex (-b/2a, (4ac-b^2)/(4a)

Answer 2

u losing me

Answer 3

First you have to solve for y

Answer 4

This is your go-by:\[y=ax ^{2}+bx=c\]That is how you determine what a and b is in above formula. The formula in the previous post represent (h,k) the vertex. Sorry for all the alphabet soup. Don't get lost, stay with me.

Answer 5

y didnt u use (x-h)^2=4p(y-k)

Answer 6

i know the answer to the problem i just dont understand how they got it

Answer 7

the answer is (0,0) focus is (0,-2) and the directrix is y=2 so how they get that

Answer 8

That is a valid method. If you don't understand that one. Try the one I posted above. It looks simpler to me.

Answer 9

how do i do the above one when i have no a and b

Answer 10

This is how you do it. I'll walk you through it. First solve for y. Put it in the form y=

Answer 11

i got -x^2/8=y

Answer 12

OK, from the formula, write your a, b, c

Answer 13

u lost me how do i do that to me they not relating im real smart but sometimes u gotta talk 2 me like im slow

Answer 14

I miswrote it the first time\[y=ax ^{2}+bx+c\]Your equation is\[y=(-1/8)x ^{2}+0x+0\]

Answer 15

ok so thats used 2 find what

Answer 16

First post message

Answer 17

ok so is b and c the vertex points

Answer 18

You choose your a, b, c. a=-1/8, b=0, c=0.
Put it in the formula {(-0/2(-1), [4(-1)(0)-0^2]/[4(-1)]} which is (0,0). (h,k) is (0,0)

Answer 19

ok so the long w u find the vertex and u use the other one to help find wast goes in the 1st formula correct???

Answer 20

I'm sorry. I didn't get that.

Answer 21

the formula u wrote at the very 1st post is that the one i need to get the vertex but i formula to get the numbers that go in the first formula

Answer 22

dat made no sense lol

Answer 23

ok both formulas u gave me is that how i get the vertext??

Answer 24

The vertex is two numbers (0,0) So the formula represent the two numbers.

Answer 25

i dont understand how you did that 1 st formula its 2 much going on wit all th () and {} [] like no how r u doing dat the vertex is (0,0) now explain to me where in the formula i get dat from cuz trying to solve that formula looks impossible

Answer 26

That is from the first formula, the first message in the post, but if you look at it long enough, you would notice your b=0, c=0, so quickly everything else ends up 0.

Answer 27

i said dat like 7 post ago ur b and c is ur h and k which is he vertex right??

Answer 28

Well not exactly. It just so happened that the zeros dominated, you could very well have a=1, b=2, c=3. That doesn't mean h=2, k=3

Answer 29

uggggggggggggggghhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh ok how do u get the focus point

Answer 30

This might help http://www.youtube.com/watch?v=ZJf9shWlMz0

Answer 31

not helping

Answer 32

ok can u start fresh with me step by step??

Answer 33

I'm not up on all that. I just had that vertex info handy in a book I have around the house. Hang out at you Math lab at school.

Answer 34

not bout 2 happen ill just give up but thanks