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Homework Help: Integral solution

  1. Nov 25, 2011 #1
    1. The problem statement, all variables and given/known data

    ∫dr/√((1/(R+r))-(1/R))

    2. Relevant equations



    3. The attempt at a solution
     
    Last edited: Nov 25, 2011
  2. jcsd
  3. Nov 25, 2011 #2

    gb7nash

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    Is the problem [itex]\int \frac{dr}{\sqrt{(\frac{1}{R}+r)-(\frac{1}{R})}}[/itex]?

    If it is, try to simplify the denominator before trying to take the integral.
     
  4. Nov 25, 2011 #3
    no,i type it wrong
    ∫dr/√((1/(R+r))-(1/R))
     
  5. Nov 25, 2011 #4

    Ray Vickson

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    So, is your integral
    [tex] \int \frac{dr}{\sqrt{\frac{1}{R+r}-\frac{1}{R}}} ? [/tex]
    If so, re-write it by first expressing
    [tex] \frac{1}{R+r}-\frac{1}{R} [/tex]
    as a simple rational expression. You should end up with an integrand of the form
    [tex] \sqrt{\frac{ar+b}{cr+d}}. [/tex]

    RGV
     
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