Mark M. answered • 12/02/20

Mathematics Teacher - NCLB Highly Qualified

y = a(x - h)^{2} + k

y = (1/16)(x - 2)^{2} - 1)

vertex at (h, k) or (2, -1)

Directrix:

y = k - p

p = 1 / 4a

p = 1 / (4)(1/16)

p = 4

y = -1 - 4

y = -5

Paul S.

asked • 12/01/20Find the directrix for the parabola

More

Mark M. answered • 12/02/20

Tutor

5.0
(243)
Mathematics Teacher - NCLB Highly Qualified

y = a(x - h)^{2} + k

y = (1/16)(x - 2)^{2} - 1)

vertex at (h, k) or (2, -1)

Directrix:

y = k - p

p = 1 / 4a

p = 1 / (4)(1/16)

p = 4

y = -1 - 4

y = -5

right off we see the vertex is (2,-1). at x=2 the distance from vertex to focus and vertex to directix does not involve x when at the vertex.

very generally when it is set that any point distance from focus and directix are equal,

the equation is ((x-x_{f})^{2})/(y_{f}-y_{d})=y-(y_{f+}y_{d}), a parabola.

y_{f}=y focus coodinate

y_{d}= y directix coordinate

two equations simultaneous

y_{f}+y_{d}=-1

y_{f}-y_{d}=16

y_{d}=-17/2 straight line horizopntal to x-axis

Paul S.

Ohh okay thank you tho
Report

12/02/20

Ask a question for free

Get a free answer to a quick problem.

Most questions answered within 4 hours.

Find an Online Tutor Now

Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.

Dayv O.

12/02/20