1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Find Points of Inflection

  1. Oct 21, 2011 #1
    1. The problem statement, all variables and given/known data

    Find the points of inflection of the graph of the function. (If an answer does not exist, enter DNE.)

    2. Relevant equations
    f(x)=1/3x^4 + 4x^3


    3. The attempt at a solution
    Found f'(x)= x^2(4/3x+12)
    Also found critical numbers to x=0 and x=-9

    I don't know how to get point of inflection
     
  2. jcsd
  3. Oct 21, 2011 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Points of inflection are where the function changes concavity. They are related to second derivatives, aren't they? Look it up.
     
  4. Oct 21, 2011 #3
    For inflection points:
    Find the second derivative of the function and set it equal to zero.

    I found that that x=-6 and x=0.

    Test some points right and left of the second derivative zeros (^) to confirm concave up or concave down. A positive value is concave up, vice versa :)
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Find Points of Inflection
  1. Find inflection point? (Replies: 5)

Loading...