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Homework Help: Question about Legendre elliptic integrals

  1. Mar 2, 2017 #1
    1. The problem statement, all variables and given/known data
    J(a, b, c;y)=∫aydx/√((x-a)(x-b)(x-c)), let a<b<c

    2. Relevant equations
    f(θ, k)=∫0θdx/√(1-k2sin2(x)), k≤1

    3. The attempt at a solution
    This is an example from my study material, and I don't understand the first step they do.
    Let x=a+(b-a)t, dx=(b-a)dt
    Wait...what? Why? How did they come to that decision. I hope there's a logical reason, otherwise how can I apply this to my other problems? I keep running into "make an educated guess." Is this another guess?
  2. jcsd
  3. Mar 4, 2017 #2
    I suggest you show a bit of unquestioning blind faith and try it.
  4. Mar 21, 2017 #3
    And that is how we discovered the new world!
  5. Mar 21, 2017 #4
    No shipwrecks or monstrous squid, I take it?
  6. Mar 21, 2017 #5
    Devoured by the Kraken, I'm afraid. Ended up dropping the course, going to spend the summer with Schaum's trying to build a better foundation for the math I need.
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