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!

Implicit Diff.

  1. Apr 6, 2008 #1

    Bo_

    User Avatar

    The problem is to find the horizontal tangent lines of an equation. Here's my attempted differentiation.

    y^2 = x^3 - x + 1

    {dy/dx} = (3x^2 - 1)/(2y)

    Correct, or no?

    i'm going to need more help going forward even if that is right, I just want to make sure it is.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Apr 6, 2008 #2
    Bo, I am pretty rusty at much of this but I will try to help since the forum is so empty at the moment.

    It looks like you got the differentiation correct.
     
  4. Apr 6, 2008 #3
    deffinitely
     
  5. Apr 6, 2008 #4

    Bo_

    User Avatar

    ok thanks, so assuming it's right, do set equal to y, then zero? In other words:

    0 = (3x^2 - 1) / 2

    and then quadratic formula using that^^^^? (remember I'm trying to find all slope zero tangent lines of the original equation.) If my procedural thinking is correct, then I don't think I need any more help, thanks.
     
  6. Apr 6, 2008 #5
    You have found the slope for any point of that function except where the slope is undefined or wherever the graph may cross itself. To find the slope you would simply plug in your x and y values. However as you said you want to know the horizontal tangents.

    You can't just simply set the y values to zero, you need to set the whole derivative to zero and solve the numerator for horizontal tangents, the denominator for vertical tangents.
     
  7. Apr 6, 2008 #6

    Bo_

    User Avatar

    I can see clearly now the rain is gone, thanks.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Implicit Diff.
  1. Implicit diff. (Replies: 7)

  2. Implicit diff? (Replies: 3)

  3. Implicit diff (Replies: 2)

  4. Implicit diff (Replies: 3)

Loading...