Question

A) x = -2
B) y =2
C) y= -2

Answer 1

Explanation:

This is a positive parabola so it opens upwards. The equation for the directrix of this parabola is y = k - p. k is the second number in the vertex of the parabola which is (0, 0), but we need to solve for p.

The form that the parabola is currently in is

`y=a(x-h)^2+k` so that means that
`a=(1)/(8)`. We can use that to solve for p in the formula

`p=(1)/(4a)` so

`p=(1)/(4((1)/(8)) )` which simplifies to

`p=(1)/((1)/(2) )` which gives us that

p = 2. Now to find the directrix:

y = k - p becomes

y = 0 - 2 so

y = -2, choice A.