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!

Homework Help: Extremum Function of a Functional

  1. Nov 13, 2011 #1
    1. The problem statement, all variables and given/known data

    J(f)=[itex]\int[/itex] 2xf−f′2+3f2f′dx

    2. Relevant equations


    3. The attempt at a solution

    Ff=2x+6f f''
    Ff'=-2f' + 6f2

    Plugging in, I get:
    2x+6f f''- [itex]\frac{d}{dx} (-2f' + 6f2)

    2x+6f f''-12f f'-2f''=0

    Which doesn't look correct to me.
    I'm guessing my mistake was in the differentiation, but I don't see it.
  2. jcsd
  3. Nov 14, 2011 #2
    I figured it out, algebra errors.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook