Question

A parabola has its vertex at (-6, 5) and focus at (-6.25, 5). Which of the following is an equation for this parabola?

Answer 1

Explanation:

vertex and focus are horizontally aligned, so parabola is horizontal.

focal length p = distance between focus and vertex = 0.25

focus lies to the left of vertex, so the parabola opens to the left.

x = a(y-k)² + h,

vertex (h,k)

a = -1/(4p)

vertex (-6,5)

h = -6

k = 5

p = 0.25

a = -1/(4·0.25) = -1

x = -(y-5)² - 6