Question

A parabola has its vertex at (2, 2), and the equation of its directrix is y = 2.5. The equation that represents the parabola is

A) x^2+4x-2y=0
B )x^2+4x+2y=0
C )x^2-4x+2y=0
D) x^2-4x-2y=0

Answer 1

c) x^2 - 4x + 2y = 0

Explanation:

For plato this is the correct answer

Answer 2

we are given with the data of a parabola with vertex at (2, 2) and directrix at y = 2.5. the formua should be ax^2 + b x + c = y because of the directrix.

(x-h)^2 = 4a (y-k)
(x-2)^2 =4a (y-2)
a is the equidistant distance from focus to vertex and from vertex to directrix that is equal to -0.5
then the answer is
(x-2)^2 =-0.5*4 (y-2)
x2 - 4x + 4 = -2y +4
x2-4x+2y = 0

answer is C