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Mathematics 21 Online
OpenStudy (vera_ewing):

Derive the equation of the parabola with a focus at (2, –1) and a directrix of y = -1/2 .

OpenStudy (vera_ewing):

@ganeshie8 f(x) = –(x – 2)^2 + 3/4 right?

ganeshie8 (ganeshie8):

x coordinate of vertex is correct

OpenStudy (vera_ewing):

@ganeshie8 and the y coordinate?

ganeshie8 (ganeshie8):

|dw:1421380941084:dw|

ganeshie8 (ganeshie8):

Notice the y coordinate of vertex has to be negative

ganeshie8 (ganeshie8):

work it again

OpenStudy (vera_ewing):

wait so then what would the answer be?

ganeshie8 (ganeshie8):

just change the sign of y coordinate of vertex in ur equation everything else looks good

ganeshie8 (ganeshie8):

f(x) = -(x - 2)^2 - 3/4

OpenStudy (vera_ewing):

THank you!

ganeshie8 (ganeshie8):

yw

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