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Integral of 1/x = ln(x) Problem has missing absolute value?

  1. Sep 4, 2011 #1
    Integral of 1/x = ln(x)... Problem has missing absolute value!?

    This is an ODE problem and solution, but what I'm not understanding here is calculus based:

    2rwatya.jpg

    Why does the argument to the red-boxed ln() not in absolute value signs?? ( | | )
    u = cos(t) so the numerator can be negative. I am just confused as to why they left that out.

    Thanks for any help.
     
    Last edited: Sep 4, 2011
  2. jcsd
  3. Sep 5, 2011 #2
    Re: Integral of 1/x = ln(x)... Problem has missing absolute value!?

    My solution is that, it is an Initial value problem, (there is only one t which we care about) and with that t the argument in the natural log is positive and so u can ignore the abs value!
     
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