Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A question on limits

  1. Oct 25, 2011 #1
    I need help with this question. I understand that logic behind it; as P approaches O the value the right bisector Q reaches it's maximum. I don't know how to show this algebraically however. Help?
     

    Attached Files:

  2. jcsd
  3. Oct 25, 2011 #2

    micromass

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    Insights Author

    We give P the coordinates (x,y). We know that P is on the parabola, so we know that

    [tex]P=(x,x^2)[/tex]

    Now, can you find the coordinates of the point Q??
     
  4. Oct 25, 2011 #3
    Ok, so the bisector would intersect P at point x/2. Because I know that the x coordinate on Q is 0, how would I find it's y?
     
  5. Oct 25, 2011 #4

    micromass

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    Insights Author

    Answer the following steps:

    - Find the midpoint M between 0 en P.
    - Find the equation of the line L going through 0 and P
    - Find a vector perpendicular to the line L
    - Construct the equation of the line R going through M and perpendicular through L
    - Find Q as the intersection between R and the y-axis.

    All of these questions involve nothing more than 10th grade geometry. So you should be able to complete these easily.
     
  6. Oct 25, 2011 #5
    How do I show algebraically that Q approaches infinity as P approaches the origin?
     
  7. Oct 26, 2011 #6

    micromass

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    Insights Author

    It doesn't approach infinity.

    Did you find the expression for Q?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Similar Discussions: A question on limits
  1. Limit question ! (Replies: 2)

  2. Limit question (Replies: 10)

  3. Limits question (Replies: 6)

  4. Limit question (Replies: 3)

  5. Limits question (Replies: 5)

Loading...