Results 1 to 3 of 3

Math Help - differentiation tangent lines question

  1. #1
    Member
    Joined
    May 2008
    Posts
    76

    differentiation tangent lines question

    How many tangent lines to the curve y=x/(x+1) pass through the point (1,2)? At which points do these tangent lines touch the curve?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member flyingsquirrel's Avatar
    Joined
    Apr 2008
    Posts
    802
    Hi
    Quote Originally Posted by cityismine View Post
    How many tangent lines to the curve y=x/(x+1) pass through the point (1,2)? At which points do these tangent lines touch the curve?
    Let f(x)=\frac{x}{x+1}

    The equation of the tangent line to the curve of f at a is y=f(a)+(x-a)f'(a). As you're looking for the tangent lines which pass through (1,2), you've to find the solutions of 2=f(a)+(1-a)f'(a). Can you take it from here ?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    May 2008
    Posts
    76
    I took it from exactly where you left it. The answer I got matches the one in the book, so I know it's right.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Question about tangent lines to circles...
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: February 20th 2010, 01:40 PM
  2. Implicit differentiation and tangent lines
    Posted in the Calculus Forum
    Replies: 4
    Last Post: October 8th 2009, 03:38 PM
  3. Implicit Differentiation, Tangent Lines
    Posted in the Calculus Forum
    Replies: 3
    Last Post: January 25th 2009, 03:12 PM
  4. Replies: 4
    Last Post: January 15th 2009, 04:54 AM
  5. Question about Tangent lines
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 22nd 2008, 08:48 AM

Search Tags


/mathhelpforum @mathhelpforum