A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • 5 years ago

Find where the function is concave up: f(x) = 3x4 - 2x3 – 3x

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

    So far I did find f '(x)which equals 12x^3-6x^2-3

  2. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    f'' is a good test for cave up....which is a MIN find your "zeros" for the f' and that will tell you what "x" values you need to use for the next part..

  3. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    3(4x^3 -2x^2 -1) narrows it down. 4x^3 -2x^2 -1 = 0 x^2(4x-2) = 1 might help

  4. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    lets go ahead and find the f'' might be easier

  5. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    f'' = 36x^2 - 12x now we can partition this out to determine what values we get for the number line

  6. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    12x(3x -1).... we have zero values at 0 and 1/3 these are out inflections if were lucky <........0.........1/3..........> - + + - - + ---------------------- + - + getting warmer

  7. amistre64
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    0 and 1/3 are our inflections were the concavity changes (-inf,0) = cave up (0,1/3) = cave down (1/3, inf) = cave up so this thing looks like a "W"

  8. 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.