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jimthompson5910 (jim_thompson5910):
plug all this info into
( (y-k)^2 )/(a^2) - ( (x-h)^2 )/(b^2) = 1
OpenStudy (smokeysthename):
do i need to find x and y?
jimthompson5910 (jim_thompson5910):
no
jimthompson5910 (jim_thompson5910):
those are variables that have no fixed value
OpenStudy (smokeysthename):
|dw:1365630292428:dw|
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jimthompson5910 (jim_thompson5910):
good, and you can rewrite (y-0)^2 as just y^2, but that's optional
OpenStudy (smokeysthename):
okk cool (: i have 2 more
jimthompson5910 (jim_thompson5910):
ok
OpenStudy (smokeysthename):
OpenStudy (smokeysthename):
can you just quickly go through these cause i gotta go leave for work in 9 minutes.
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jimthompson5910 (jim_thompson5910):
oh well we can do this later then
jimthompson5910 (jim_thompson5910):
I'm still tracking down the formulas we'll need
jimthompson5910 (jim_thompson5910):
sound good?
OpenStudy (smokeysthename):
nooo i gotta get this done :(
jimthompson5910 (jim_thompson5910):
ok
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jimthompson5910 (jim_thompson5910):
Here's how I think it should be done, but don't have enough time to confirm
OpenStudy (smokeysthename):
no need to confirm. it'll be fine
jimthompson5910 (jim_thompson5910):
x + 5y^2 = 0
x = -5y^2
(x - 0) = -5(y-0)^2
(-1/5)(x - 0) = (y-0)^2
-4(1/20)(x - 0) = (y-0)^2
p = 1/20 ---> focal length is 1/20
jimthompson5910 (jim_thompson5910):
The vertex is (0,0) since h = 0 and k = 0
jimthompson5910 (jim_thompson5910):
The directrix is y = 1/20 since you add 1/20 to the x coordinate of the center
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jimthompson5910 (jim_thompson5910):
Oh sorry, I meant to say x = 1/20 instead of y = 1/20
jimthompson5910 (jim_thompson5910):
The focus is (-1/20, 0) since you go 1/20 units to the left of the center
OpenStudy (smokeysthename):
okay makes sense.. last one
jimthompson5910 (jim_thompson5910):
how much time do we have?
OpenStudy (smokeysthename):
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OpenStudy (smokeysthename):
about 5 minutes.
jimthompson5910 (jim_thompson5910):
ok then I'll make it quick
OpenStudy (smokeysthename):
kk
jimthompson5910 (jim_thompson5910):
multiply every term by the LCD 2x to get
3*2x = 6x
(3/x)*2x = 6x/x = 6
(1/2)*2x = 2x/2 = x
(1/x)*2x = 2x/x = 2
-------------------------------------------------------
So the expression simplifies to
6x - 6
------
x - 2
OpenStudy (smokeysthename):
that makes sense!
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