what is the focus of the parabola
[tex]y = - \frac{1}{4} {x}^{2} - 2x - 2[/tex]
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I've seen so many wrong answers and I got it wrong on my quiz

answer: (-4,1)​

Respuesta :

Answer:

(-4,1)

Step-by-step explanation:

The given parabola is

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

When we rewrite in vertex form, we get;

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

Or

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

When we compare to:

[tex]{(x - h)}^{2} = 4p( y - k)[/tex]

We have 4p=-4

This means p=-1

But the vertex is at:

(-4,2)

Since it is a vertical parabola that opens down, the focus is one unit(|p|=1) below the vertex.

Hence the focus is (-4,1)