1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Tangent Line

  1. Oct 2, 2007 #1
    [SOLVED] Tangent Line

    1. The problem statement, all variables and given/known data
    Find all tangent lines that are tangent to Y=x^2 and go through the point (2,3)

    2. Relevant equations

    3. The attempt at a solution

    At first I thought I knew how to do this problem, I found the derivative of the equation got:

    y' = 2x ; then I plugged in x=2 to find the slope of the tangent however then i realized this is not the correct point to plug in because this is not the point that the line is actually going to be hitting the original graph at; I don't know how you would find this said point to plug in for x to get the slope can anyone steer me in the right direction
  2. jcsd
  3. Oct 2, 2007 #2


    User Avatar
    Science Advisor
    Homework Helper

    You are looking for a line. You have the slope, and a point that the line goes through. That's sufficient information to derive the line equation.
  4. Oct 2, 2007 #3
    I don't have the slope though because I don't know what point the line is tangent to on the curve so how can i plug a value into the derivative to get slope
  5. Oct 2, 2007 #4


    User Avatar
    Science Advisor
    Homework Helper

    y' = 2x is the family of all lines that are tangent to x^2. You are supposed to find the one that goes through (2,3).
  6. Oct 2, 2007 #5
    oh i see thank you for your help :)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Tangent Line
  1. Tangent Line (Replies: 4)

  2. Tangent Line (Replies: 6)

  3. Tangent lines (Replies: 1)

  4. Tangent of a line (Replies: 14)

  5. Tangent line (Replies: 4)