Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Point of inflection question

  1. Oct 25, 2006 #1
    Hi guys... I have this problem that i need to verify. I did it but i just want one of you guys to maybe check to see if it is correct.

    problem: find the points of inflection on the curve

    y = -3x^4 + 4x^3 +36x^2

    so first i found y'' = -36x^2 + 24x + 72 = 0
    since b^2 - 4ac is not a perfect square i had to use the formula
    x = [ -b + sqrt(b^2 - 4ac) ]/2a
    and
    x = [ -b - sqrt(b^2 - 4ac) ]/2a

    by using these i get the values of x as
    x = -1.1196
    and x = 1.7863

    so the points of inflection are (-1.1196, 34.79) and (1.7863, 107.12)

    Thanks in advance
     
  2. jcsd
  3. Oct 25, 2006 #2
    Perfect :).
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook