Results 1 to 2 of 2

Math Help - tangent line equation from a gradient vector

  1. #1
    Member
    Joined
    Oct 2007
    Posts
    159

    tangent line equation from a gradient vector

    Throughout our vector calculus class, we have used
    tangent line equation = f(a,b) + f sub x (a,b)(x-a) + f sub y(a,b) (y-b)

    On an old final the question is asked to find the equation for the tangent line to a function who's output at (1,3) is = 7 and who's gradient vector (1,3) = 2 i - 5 j

    Needless to say since I do not have the function I can not use my nice canned equation to solve this one!

    The question is then asked to find the tangent plane to the surface of z = f(x,y) at the point (1,3,7). NO other information is provided?????

    I believe in the first question that my gradient vector would be providing how x and y are changing so I should be able to get a slope for my line out of it. I am really not sure how to proceed. Any nudges or pushes toward the solution would be appreciated very much! Frostking
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Nov 2008
    From
    France
    Posts
    1,458
    Hi

    The gradient vector at (1,3) is 2i - 5j
    Therefore \frac{\partial f}{\partial x}(1,3) = 2 and \frac{\partial f}{\partial y}(1,3) = -5
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 6
    Last Post: January 12th 2011, 03:38 PM
  2. Vector Tangent Line Problem
    Posted in the Calculus Forum
    Replies: 1
    Last Post: November 4th 2010, 02:46 PM
  3. Replies: 6
    Last Post: July 23rd 2010, 01:36 PM
  4. direction vector for a tangent line to a curve
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 16th 2009, 12:10 AM
  5. Equation of line & Gradient qus.
    Posted in the Calculus Forum
    Replies: 9
    Last Post: April 17th 2006, 03:32 AM

Search Tags


/mathhelpforum @mathhelpforum