Question

can anyone explain how to do parabola's in great detail

Answer 1

yeah..fire away

Answer 2

wat d u want to know exactly?

Answer 3

study all the four standard forms and the general forms of parabolae carefully...learn how to evaluate the vertex, latusrectum and directrix and focus and centre

Answer 4

how to figure out the vertex directrix and focus if they only give me a lil information

Answer 5

giv me d info

Answer 6

vertex (-2,0) directrix y=-4 and i have 2 find the equation and graph it

Answer 7

(x+2)^2= 16y

Answer 8

ok now can u teach me how to get that

Answer 9

sure

Answer 10

u c if u have d directrix parallel to x-axis, its a vertical parabola
upward or dwnward

Answer 11

since here d vertex lies above d directrix its an upward parabola

Answer 12

ok so do i use (x-h)^2=4p(y-k)

Answer 13

yeah bingo...where p is the distance btween d vertex and directrix

Answer 14

got it?

Answer 15

no i just know the formula 2 use but idk how 2 use it

Answer 16

well now u kno

Answer 17

no i dont how did u get the answer wat are the steps wat did u plug in

Answer 18

u kno d formula...jst remmbr u use dis only when the directrix is parallel to x-axis

Answer 19

when d directrix is y=something, u use it

Answer 20

ok but wat steps did u take to get the answer i knoow 2 use the fromula but idk how 2 get the answer

Answer 21

see h and k are the x and y co-ordinates of the vertex. and p is the distance of the vertex from directrix

Answer 22

so far all i have is (x-2)^2=4py

Answer 23

so p=3???

Answer 24

p is 4
the distance of -2,0 from y=-4

Answer 25

so p=-4

Answer 26

4
distance is always positive

Answer 27

ok

Answer 28

so uve got (x+2)^2 = 4.4(y)

Answer 29

thanks do you mind helping me wit some more

Answer 30

no i dont..

Answer 31

(x+2)^2=16y

Answer 32

wat i got

Answer 33

thats ryt i spose

Answer 34

focus (0,0) directrix x=4

Answer 35

hold on on dat last one was my parabola suppose 2be upward and my directrix was suppose 2 go through it right???

Answer 36

no ur getting muddled up..the directrix doesnt go thru d parabola

Answer 37

well when i graphed it it did cuz the y axis is vertical and not horizontial so is my parabola not facing the right way

Answer 38

no ur parabola shld touch the x-axis, pass thru -2,0 and the directrix should be 4 units below it

Answer 39

ok i had it right the 1st time so on to the next one lol

Answer 40

ws i wrong?

Answer 41

idk lol idc 4real im sick of dis class

Answer 42

ready 2 help me wit the other 1

Answer 43

yeah

Answer 44

focus (0,0) directrix x=4

Answer 45

wat way will the directrix be going

Answer 46

vertical

Answer 47

ok

Answer 48

now 2 figure out the equation do i use (y-k)^2=4p(x-h)

Answer 49

and is this going 2 be opening to the left

Answer 50

ur right...u do it quite well..yr u sick of it?

Answer 51

y^2=-16x

Answer 52

cuz idk how 2 do it im just guessing

Answer 53

no bt ur guessin right so u shld get confidence

Answer 54

so wat is the vertex and if i dont have (h,k) do i use x,y

Answer 55

use 0,0 for h,k..so its y^2=-16x

Answer 56

ok so anytime i dont have the vertex use 0,0

Answer 57

bt ur vertex is given 0,0

Answer 58

dat was the focus

Answer 59

OH IMSORRY

Answer 60

rly sorry..bt u cn frgv a lovesick man cant u...

Answer 61

lol sure so how do i do it

Answer 62

neway so the vertex is the midpt of the focus and the pt where d directrix meets the axis

Answer 63

i need numbers to do the formula

Answer 64

so its d midpt of 0,0 and 4,0

Answer 65

so the vertex is 2,0

Answer 66

oooooo ok but y lol

Answer 67

ur having fun arent u...d midpt of 0,0 and 4,0 is (0+4)/2, 0+0/2

Answer 68

vertex is d midpt of the focus and the directrix meeting the axis

Answer 69

u should be my teacher u making it simple my teacher is making it hard ok so i can always use dat when i am givin the focus and directrix right

Answer 70

is the answer y^2=-8px

Answer 71

thnx fr d compliment..wt grade r u in?

Answer 72

11th

Answer 73

im in ap math

Answer 74

nahi...replace d x with (x-2)

Answer 75

cz d vertex is 2,0

Answer 76

so y^2=4p(x-2)

Answer 77

yeah

Answer 78

ok dis one i did they gave me the center (-7,3) and the focus (-7,5) i got (x+7)^2=-24y is dat right

Answer 79

(x+7)^2 = 8(y-3)

Answer 80

ok

Answer 81

now the other problems r harder they gave me just a graph wit the drawing already made so i hope i can explain dis 2 u

Answer 82

try

Answer 83

the is (-4,3) and the directrix is (7,2.5)

Answer 84

ur doing somthin wrng

Answer 85

the vertex was the (-4,3)

Answer 86

is it (x-3)^2=4p(y+4)

Answer 87

yeah

Answer 88

ok

Answer 89

ok the vertex is (-2,_6) and they gave me 2.25 wat do i do

Answer 90

(-2,-6)

Answer 91

whts dis 2.25

Answer 92

x=2.25

Answer 93

so its (y+6)^2 = - 17(x+2)

Answer 94

where u get -17

Answer 95

4.25 x 4

Answer 96

where u get 4.25

Answer 97

distance of -2 from 2.25

Answer 98

u lost me now i have (y=6)^2=4p(2.25+2)