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Integrals of Trigonometric Functions

  1. Sep 20, 2009 #1
    1. The problem statement, all variables and given/known data

    I have three problems that I'm having a hard time with. I'd appreciate any help with
    any of the three problems.



    [tex]\int(x^3 * sqrt(x^2 - 1)[/tex]


    Solve for y (separation of variables):
    dy/dx = ((2y + 3)^2)/((4x + 5)^2)

    2. Relevant equations

    Separation of variables for 3rd problem.

    3. The attempt at a solution

    I have work on scartch paper but I get stuck.
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Sep 20, 2009 #2
    For the first integral, use the reduction formula for cosine.

    For the second, try u = x2

    For the third, did you try getting everything with y on one side and everything with x on the other?
  4. Sep 20, 2009 #3
    thank you. im going to try this right now. for the third i got down to an integral that would need partial fraction decomposition but got stuck. :(
  5. Sep 20, 2009 #4
    I finally got the first one. so just the 2nd and 3rd problems now.
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