Results 1 to 3 of 3

Math Help - Locus of 2 gradients?

  1. #1
    Junior Member
    Joined
    May 2006
    From
    Sydney, Australia
    Posts
    44

    Locus of 2 gradients?

    I didn't know which forum to put it in, but I thought this was the most appropriate.

    This is the question:
    Given two points A(3,-2) and B(-1,7), find the equation of the locus of P(x,y) if the gradient of PA is twice the gradient of PB.

    I've tried it 2 different ways and keep getting the same solution:
    xy + 5y + 11x - 17 = 0

    However the answer in the book says otherwise...

    Working:
    PA' = \frac{y+2}{x-3}

    PB' = \frac{y-7}{x+1}

    2 PA' = PB'

    \frac{2y+4}{x-3} = \frac{y-7}{x+1}

    ...

    xy + 5y + 11x -17 = 0
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Eater of Worlds
    galactus's Avatar
    Joined
    Jul 2006
    From
    Chaneysville, PA
    Posts
    3,001
    Thanks
    1
    I think you have your 'twice' on the wrong side.

    Try PA'=2PB'
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    May 2006
    From
    Sydney, Australia
    Posts
    44
    Quote Originally Posted by galactus
    I think you have your 'twice' on the wrong side.

    Try PA'=2PB'
    Ahh, it just clicked. I understand why the 2 is on the wrong side. Got the answer, thanks
    Last edited by chancey; August 9th 2006 at 03:16 AM.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Transfor map of gradients
    Posted in the Advanced Applied Math Forum
    Replies: 0
    Last Post: December 6th 2011, 12:10 PM
  2. Gradients
    Posted in the Algebra Forum
    Replies: 1
    Last Post: November 19th 2009, 06:21 PM
  3. gradients and y-intecept
    Posted in the Algebra Forum
    Replies: 10
    Last Post: October 13th 2009, 06:21 PM
  4. Gradients
    Posted in the Calculus Forum
    Replies: 1
    Last Post: September 24th 2008, 06:30 PM
  5. Gradients and the sort =[
    Posted in the Math Topics Forum
    Replies: 5
    Last Post: December 4th 2007, 01:19 AM

Search Tags


/mathhelpforum @mathhelpforum