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The focus of a parabola is (−6,−3) . The directrix of the parabola is y=4. What is the equation of the parabola?

The focus of a parabola is (0,−4). The directrix of the parabola is the line y=−5. What is the equation of the parabola?

The directrix of a parabola is the line y=7. The focus of the parabola is (2,3). What is the equation of the parabola?

The directrix of a parabola is y=−6. The focus of the parabola is (−2,−4) . What is the equation of the parabola?

Respuesta :

The standard equations of the parabolas are listed below:

  1. y + 6 = - (1/14) · (x + 6)²
  2. y = (1/2) · (x + 4.5)²
  3. y - 5 = - (1/8) · (x - 2)²
  4. y + 5 = (1/4) · (x + 2)²

How to determine the standard equation of the parabola

In this question we have four case of parabolas with vertical axes of reference, whose standard formula is:

[tex]y - k = \frac{1}{4\cdot p}\cdot (x-h)^{2}[/tex]     (1)

Where:

  • (h, k) - The vertex of the parabola.
  • p - Least distance between the vertex and the focus of the parabola.

Please notice that p < 0 when the directrix is above the focus, otherwise p < 0. The vertex is the midpoint of line segment between the directrix and the focus.

Now we proceed to derive the standard equations of the parabola:

1) Vertex:

(h, k) = 0.5 · (- 6, 4) + 0.5 · (- 6, - 3)

(h, k) = (- 6, 0.5)

Least distance:

p = - 3.5

y + 6 = - (1/14) · (x + 6)²

2) Vertex:

(h, k) = 0.5 · (0, - 4) + 0.5 · (0, - 5)

(h, k) = (0, - 4.5)

Least distance:

p = 0.5

y = (1/2) · (x + 4.5)²

3) Vertex:

(h, k) = 0.5 · (2, 3) + 0.5 · (2, 7)

(h, k) = (2, 5)

Least distance:

p = 2

y - 5 = - (1/8) · (x - 2)²

4) Vertex:

(h, k) = 0.5 · (- 2, - 6) + 0.5 · (- 2, - 4)

(h, k) = (- 2, - 5)

Least distance:

p = 1

y + 5 = (1/4) · (x + 2)²

To learn more on parabolas: https://brainly.com/question/4074088

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