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Mathematics 21 Online
OpenStudy (anonymous):

Find the standard form of the equation of the parabola with a focus at (0, -2) and a directrix at y = 2. https://i.gyazo.com/3a74217c9b4bc16836574bddf8afe2c0.png

OpenStudy (welshfella):

the curve passes through the origin and as the focus is negative it opens downwards standard form of this type is x^2 = 4ay where a = focus so can you work it out?

OpenStudy (anonymous):

ok give me sec

OpenStudy (anonymous):

am i plugging in -2?

OpenStudy (welshfella):

yes I should have said a = y-coordinate of the focus

OpenStudy (anonymous):

ok

OpenStudy (anonymous):

x^2 = 4(-2)y x^2 = -8y

OpenStudy (welshfella):

ok so far the standard form is y =

OpenStudy (welshfella):

so divide both sides by -8

OpenStudy (anonymous):

y = (x^2)/-8

OpenStudy (welshfella):

yea thats ok but its usually written as |dw:1439835011279:dw|

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