Question

Derive the equation of the parabola with a focus at (4, -7) and a directrix of y = -15. Put the equation in standard form

Answer 1

a. f(x) = 1/16 x2 - 8x + 11
b. f(x) = 1/16 x2 - 8x - 10
d. f(x) = 1/16 x2 - 1/2 x - 10

Answer 2

C was wrong

Answer 3

well you need to find the vertex.

but before that you need to find the focal length

the distance between the directrix and focus is equal to 2 times the focal length.

so what do you think the focal length would be..?

Answer 4

I'm totally lost! The practice problems don't make sense at all:(

Answer 5

And in the lesson it didn't say anything about needing the vertex or focal length I don't think

Answer 6

ok...


the vertex in the line x = 4 and located half way between y = -7 and y = -15

the total distance between y = -7( the focus) and y = -15( the directrix) is a length which is double the focal length