Type the correct answer in each box. Use numerals instead of words. If necessary, use / for the fraction bar.

The focus of a parabola is [tex]$(0, -2)$[/tex]. The directrix is the line [tex]$y = 0$[/tex]. What is the equation of the parabola in vertex form?

In the equation [tex]$y = \frac{1}{4p}(x - k)^2 + h$[/tex], the value of [tex]$p$[/tex] is [tex]$\square$[/tex].

The vertex of the parabola is the point ([tex]$\square$[/tex], [tex]$\square$[/tex]).

The equation of this parabola in vertex form is [tex]$y = \square x^2 - 1$[/tex].



Answer :

To find the equation of the parabola given the focus and directrix, let's proceed with the following steps:

1. Determine the value of [tex]\( p \)[/tex]:

[tex]\[ p = \frac{\text{distance from the vertex to the focus or directrix}}{2} \][/tex]

Here, the focus is at [tex]\( (0, -2) \)[/tex] and the directrix is the line [tex]\( y = 0 \)[/tex]. The distance between the focus and the directrix is 2 units.

[tex]\[ p = \frac{-2 - 0}{2} = -1 \][/tex]

So, the value of [tex]\( p \)[/tex] is [tex]\(-1\)[/tex].

2. Determine the vertex of the parabola:

The vertex is located midway between the focus and the directrix. Since the focus is at [tex]\( (0, -2) \)[/tex] and the directrix is [tex]\( y = 0 \)[/tex], the vertex is:

[tex]\[ \left( 0, \frac{-2 + 0}{2} \right) = (0, -1) \][/tex]

3. Formulate the equation of the parabola in vertex form [tex]\( y = \frac{1}{4p}(x - h)^2 + k \)[/tex]:

For the given parabola:

- [tex]\( p = -1 \)[/tex]
- Vertex, [tex]\( (h, k) = (0, -1) \)[/tex]

[tex]\[ y = \frac{1}{4(-1)}(x - 0)^2 + (-1) \][/tex]
[tex]\[ y = -\frac{1}{4}x^2 - 1 \][/tex]

Now, fill in the boxes with the obtained values:

In the equation [tex]\( y = \frac{1}{4p}(x - h)^2 + k \)[/tex], the value of [tex]\( p \)[/tex] is [tex]\( \boxed{-1} \)[/tex]
The vertex of the parabola is the point [tex]\( ( \boxed{0} \ \boxed{-1} ) \)[/tex]
The equation of this parabola in vertex form is [tex]\( y = \boxed{-\frac{1}{4}} x^2 - 1 \)[/tex]