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How to integrate K/[(y^2 + K)^3/2] dy

  1. Sep 24, 2011 #1
    As you can see the function given is

    K/[(y2 + K)1.5]

    The integral of this equation with respect to dy is part of the explanation my textbook gives of finding electric field due to line of uniformly charged wire, where y of course is the variable length of the wire. Then it gives the integral as

    y/[d(y2 + k2)0.5]

    but I can't see how it got this, since I try to differentiate this answer and got back this function which was different to the original.

    Can someone whow me how the text book got that answer? Thanks.
    This function is radically different

    Here is a picture of the original textbook statement.

    [PLAIN]http://desmond.imageshack.us/Himg97/scaled.php?server=97&filename=physicsq.png&res=medium [Broken]
     
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Sep 24, 2011 #2
    integrate ((y^2 + K)^-3/2)dy=dv to get -((y^2 + K)^-1/2)/y=v

    then

    multiply that times K and you should be able to get the right answer since K is constant right?

    this is just what I think
     
  4. Sep 24, 2011 #3
    Never mind, I found out what I did wrong. I misused the product rule. What a simple mistake.
     
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