A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Help will give a medal! What is the equation of the quadratic graph with a focus of (−4, 17/8) and a directrix of y = 15/8? f(x) = −2x^2 + 16x − 24 f(x) = −2x^2 + 15x − 2 f(x) = 2x^2 + 12x − 10 f(x) = 2x^2 + 16x + 34

  • This Question is Closed
  1. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @welshfella

  2. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @DeltaForce @DecentNabeel @pokamons @AmyRoseRules

  3. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @PeachesP

  4. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @Loser66 ?

  5. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    he word directrix is the clue that we are dealing with a parabola. A parabola is a set of points that are equally distant from the focus (a,b) and the directrix d. So for each point (x,y) on the parabola: (x - a)^2 + (y - b)^2 = (y - d)^2 x^2 - 2ax + a^2 + y^2 - 2by + b^2 = y^2 - 2dy + d^2 Subtract y^2 from both sides... x^2 - 2ax + a^2 - 2by + b^2 = -2dy + d^2 Now I would just substitute in the the values (a = -4, b = 17/8, d = 15/8)... x^2 - 2(-4)x + (-4)^2 - 2(17/8)y + (17/8)^2 = -2(15/8)y + (15/8)^2 Simplify... x^2 + 8x + 16 - (17/4)y + 289/64 = -(15/4)y + 225/64 Add (17/4)y to both sides... x^2 + 8x + 16 + 289/64 = (2/4)y + 225/64 x^2 + 8x + 16 + 289/64 = (1/2)y + 225/64 Subtract 225/64 from both sides... x^2 + 8x + 16 + 1 = (1/2)y x^2 + 8x + 17 = (1/2)y Multiply both sides by 2... 2x^2 + 16x + 34 = y ...which is equal to equation D.

  6. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thanks for the help!

  7. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    :D

  8. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Romnay said it perfectly, its almost exact to what i would say

  9. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.