Results 1 to 4 of 4

Math Help - Equation of tangent line

  1. #1
    Newbie
    Joined
    Mar 2010
    Posts
    11

    Question Equation of tangent line

    Hey guys, hope I can get some help on this problem that I've been stuck on.

    Find the equation of the tangent line to the given curve at the specific point.
    y ln y = x, (0,1)

    Thanks.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,407
    Thanks
    1294
    Quote Originally Posted by drahcirnaw View Post
    Hey guys, hope I can get some help on this problem that I've been stuck on.

    Find the equation of the tangent line to the given curve at the specific point.
    y ln y = x, (0,1)

    Thanks.
    \frac{d}{dx}(y\ln{y}) = \frac{d}{dx}(x)

    \frac{d}{dy}(y\ln{y})\,\frac{dy}{dx} = 1

    \left(y\frac{1}{y} + \ln{y}\right)\frac{dy}{dx} = 1

    (1 + \ln{y})\frac{dy}{dx} = 1

    \frac{dy}{dx} = \frac{1}{1 + \ln{y}}.


    So at the point (0, 1)

    \frac{dy}{dx} = \frac{1}{1 + \ln{1}}

     = \frac{1}{1 + 0}

     = 1.



    So now you have the gradient of the tangent and a point on the tangent line.

    y = mx + c

    1 = 1(0) +c

    c = 1.


    So the tangent line is y = x + 1.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member
    Joined
    Dec 2009
    From
    1111
    Posts
    872
    Thanks
    3
    Quote Originally Posted by drahcirnaw View Post
    Hey guys, hope I can get some help on this problem that I've been stuck on.

    Find the equation of the tangent line to the given curve at the specific point.
    y ln y = x, (0,1)

    Thanks.
    Dear drahcirnaw,

    When I had written my answer Prove it had already posted his one. Therefore I deleted it.
    Last edited by Sudharaka; March 11th 2010 at 11:19 PM. Reason: The answer is already given
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Mar 2010
    Posts
    11
    Thanks for the help. Cleared up my problems.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Equation of line tangent to G
    Posted in the Calculus Forum
    Replies: 11
    Last Post: April 30th 2011, 06:35 PM
  2. Replies: 6
    Last Post: January 12th 2011, 02:38 PM
  3. Equation of the Tangent Line
    Posted in the Calculus Forum
    Replies: 3
    Last Post: October 21st 2010, 09:10 PM
  4. Equation of a tangent line
    Posted in the Calculus Forum
    Replies: 2
    Last Post: February 18th 2009, 06:49 PM
  5. tangent line equation
    Posted in the Calculus Forum
    Replies: 6
    Last Post: April 10th 2008, 01:29 PM

Search Tags


/mathhelpforum @mathhelpforum