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Homework Help: Differenciate twice or integrate twice?

  1. Sep 10, 2010 #1
    I am confuse a question state f(x) = (ln x )^2 .... i skip a part..

    show that f'' (x) = 0 (not concern with the answer but what does f'' means is it that i have to differenciate twice or integrate twice..??)

    my second question: how to differenciate y = (ln x )^2
  2. jcsd
  3. Sep 10, 2010 #2


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    Gold Member

    Re: differenciation

    It means differentiate twice.

    To actually do it, think about using the chain rule...
  4. Sep 10, 2010 #3
    Re: differenciation

    chain rule that is dy/dx = dy/dt x dt/dx of course i must apply it
  5. Sep 11, 2010 #4


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    Science Advisor

    Re: differenciation

    Yes, and with y = (ln x )^2 , t= ln x so you want (d(t^2)/dt)(d ln(x)dx)
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