Results 1 to 6 of 6
Like Tree2Thanks
  • 1 Post By SlipEternal
  • 1 Post By Prove It

Math Help - Integral involving a surd .

  1. #1
    Member
    Joined
    Apr 2009
    Posts
    91

    Integral involving a surd .

    How would you go about solving this one:
    integral (y*sqrt(2-(2y)^2)) dy
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Nov 2010
    Posts
    1,935
    Thanks
    784

    Re: Integral involving a surd .

    Try a u-substitution.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Apr 2009
    Posts
    91

    Re: Integral involving a surd .

    I have tried that a couple of ways.

    u=(2-(2y)^2) and also u=4y^2..........cant get it to work...what was your intended u sub.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Nov 2010
    Posts
    1,935
    Thanks
    784

    Re: Integral involving a surd .

    u = 2-(2y)^2

    du = -4ydy

    dy = \dfrac{du}{-4y}

    \int y\sqrt{2-(2y)^2}dy = \int y\sqrt{u}\dfrac{du}{-4y} = -\dfrac{1}{4}\int u^{1/2}du
    Thanks from heatly
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,831
    Thanks
    1602

    Re: Integral involving a surd .

    Quote Originally Posted by heatly View Post
    How would you go about solving this one:
    integral (y*sqrt(2-(2y)^2)) dy
    I'd lean towards making the substitution \displaystyle \begin{align*} 2y = \sqrt{2}\sin{(\theta)} \implies dy = \frac{\sqrt{2}}{2}\cos{(\theta)}\,d\theta \end{align*}...
    Thanks from heatly
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Member
    Joined
    Apr 2009
    Posts
    91

    Re: Integral involving a surd .

    Thanks a lot
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Problem involving in surd
    Posted in the Algebra Forum
    Replies: 3
    Last Post: August 13th 2012, 10:18 AM
  2. Integral involving erf x
    Posted in the Calculus Forum
    Replies: 0
    Last Post: May 17th 2012, 08:21 AM
  3. Integral involving lnx
    Posted in the Calculus Forum
    Replies: 8
    Last Post: October 20th 2011, 03:38 PM
  4. Integral problem involving the definition of the integral
    Posted in the Differential Geometry Forum
    Replies: 1
    Last Post: May 23rd 2011, 08:06 AM
  5. Integral involving e^(-x^2).
    Posted in the Calculus Forum
    Replies: 10
    Last Post: April 14th 2010, 05:20 PM

Search Tags


/mathhelpforum @mathhelpforum