Results 1 to 3 of 3

Math Help - Slope of a curve at a point

  1. #1
    Member
    Joined
    Sep 2008
    Posts
    114

    Slope of a curve at a point

    Find the equation of the tangent line to f(x)=X^2 that passes through the point (0, -4)

    I only know how to find the equation of the tangent line AT a certain point

    There are 2 possibilities I'm guessing but I'm not sure how to find them.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Oct 2009
    Posts
    5,561
    Thanks
    785

    Re: Slope of a curve at a point

    Let (x, x^2) be the point of tangency. Then the slope of the line is 2x. From the following picture you can find x.

    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member TheChaz's Avatar
    Joined
    Nov 2010
    From
    Northwest Arkansas
    Posts
    600
    Thanks
    2

    Re: Slope of a curve at a point

    Alternatively, use the point-slope formula for the line through (0, -4) with slope m.
    y + 4 = m(x - 0)
    Since y = x^2 and m = y' = 2x, we have
    x^2 + 4 = 2x(x)
    so 4 = x^2
    x = +/-2...
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Linear Problem - Slope of Curve Through Point
    Posted in the Differential Equations Forum
    Replies: 2
    Last Post: September 13th 2011, 11:56 AM
  2. Replies: 6
    Last Post: May 16th 2011, 05:57 AM
  3. Replies: 2
    Last Post: November 5th 2010, 02:34 PM
  4. Replies: 1
    Last Post: February 7th 2010, 01:47 PM
  5. Replies: 1
    Last Post: January 26th 2009, 06:13 PM

Search Tags


/mathhelpforum @mathhelpforum