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Homework Help: How to integrate int (x^2 + 4)^(-1/2) dx Is it a substitution?

  1. Jun 20, 2005 #1
    I need help antidiffing this equation:

    i have tried subbing u=x^2+4 i have tried subbing u= (x^2+4)^(-1/2).
    i have tried making x the subject. even tried to use partial fraction, with no avail, because i could not figure out how to use partially factorize it.
    If anyone could lead me towards the right answer.
  2. jcsd
  3. Jun 20, 2005 #2


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    Homework Helper

    Whenever you have an integrand that looks like the Pathagoras theorem, use trig substitutions. You know, draw a right triangle with theta in it. Then the hypotneuse is the radical, one side is 2, the other is x right. Follow through: What would the tan(theta) be?
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