Results 1 to 2 of 2

Math Help - Integration Using Hyperbolic Identities

  1. #1
    Newbie
    Joined
    Nov 2010
    Posts
    20

    Integration Using Hyperbolic Identities

    So i need to solve:

    The integral of 1/ Sqrt( 9x^2 - 16) dx

    If the 9 wasnt infront of x^2, i could easily do it, letting x = 4cosh(u) and so on, but the 9 confuses me.

    Am i right in thinking i take a 9 out, to leave :

    1/ sqrt( 9(x^2 - 16/9) ) dx and then: (1/3) * Integral of 1/ sqrt(x^2 - 16/9) dx?

    As when i tried this, i got the incorrect answer.

    Also, apologies if the format is difficult to understand, i tried to use latex, but got ' Latex Error: Compile failed'

    Thanks
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    10,184
    Thanks
    403
    Awards
    1
    Quote Originally Posted by Mcoolta View Post
    So i need to solve:

    The integral of 1/ Sqrt( 9x^2 - 16) dx

    If the 9 wasnt infront of x^2, i could easily do it, letting x = 4cosh(u) and so on, but the 9 confuses me.

    Am i right in thinking i take a 9 out, to leave :

    1/ sqrt( 9(x^2 - 16/9) ) dx and then: (1/3) * Integral of 1/ sqrt(x^2 - 16/9) dx?
    So far so good. Now make the substitution x = sqrt(16/9)*cosh(u) = (4/3)*cosh(u). This gives dx = (4/3)*sinh(u) du, so the integral becomes




    Can you take it from here?

    -Dan
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Hyperbolic trig identities?
    Posted in the Calculus Forum
    Replies: 3
    Last Post: August 3rd 2011, 06:06 AM
  2. Hyperbolic Identities
    Posted in the Calculus Forum
    Replies: 2
    Last Post: September 16th 2009, 07:25 AM
  3. Hyperbolic Function Identities
    Posted in the Calculus Forum
    Replies: 2
    Last Post: September 12th 2009, 02:20 PM
  4. hyperbolic integration
    Posted in the Calculus Forum
    Replies: 4
    Last Post: March 6th 2008, 09:44 PM
  5. proving hyperbolic Identities
    Posted in the Calculus Forum
    Replies: 4
    Last Post: January 28th 2007, 08:08 AM

Search Tags


/mathhelpforum @mathhelpforum