Results 1 to 4 of 4
Like Tree2Thanks
  • 1 Post By Shakarri
  • 1 Post By Shakarri

Math Help - Prove Each Statement

  1. #1
    Super Member nycmath's Avatar
    Joined
    Jan 2013
    From
    New York City
    Posts
    610
    Thanks
    7

    Prove Each Statement

    Suppose that the circle
    x^2 + 2Ax + y^2 + 2By = C has two x-intercepts, xsub1 and xsub2 and two y-intercepts, ysub1 and ysub2. Prove each statement.

    (a) (xsub1+xsub2)/(ysub1+ysub2) equals A/B

    (b) (xsub1)(xsub2) - (ysub1)(ysub2) = 0

    (c) (xsub1)(xsub2)+(ysub1)(ysub2) = -2C
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Oct 2012
    From
    Ireland
    Posts
    591
    Thanks
    159

    Re: Prove Each Statement

    What did you do to try and prove the statements? Hint: at the x-intercept y=0.
    Thanks from nycmath
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member nycmath's Avatar
    Joined
    Jan 2013
    From
    New York City
    Posts
    610
    Thanks
    7

    Re: Prove Each Statement

    Can you at least get me started by proving part (a)?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member
    Joined
    Oct 2012
    From
    Ireland
    Posts
    591
    Thanks
    159

    Re: Prove Each Statement

    At the x-intercept when y=0 the two points are (x1,0) and (x2,0).
    Putting y=0 into the equation of the circle you get x2+2Ax-C=0

    Solving this quadratic equation for x you get x=\frac{-2A\pm \sqrt{(2A)^2+4C}}{2}=\frac{-2A\pm \sqrt{4(A^2+C)}}{2}=\frac{-2A\pm 2\sqrt{A^2+C}}{2}
    x=-A\pm \sqrt{A^2+C}

    Therefore, x_1=-A+ \sqrt{A^2+C} and x_2=-A- \sqrt{A^2+C}

    That should be enough to get you started
    Thanks from nycmath
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. How to prove an IFF (If and only If) statement!
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: January 15th 2013, 07:49 AM
  2. prove or disprove: statement about Span
    Posted in the Advanced Algebra Forum
    Replies: 7
    Last Post: December 29th 2012, 09:28 AM
  3. prove or disprove: statement about Span
    Posted in the Advanced Algebra Forum
    Replies: 2
    Last Post: December 25th 2012, 12:00 PM
  4. Is this a true statement? Can you prove?
    Posted in the Discrete Math Forum
    Replies: 3
    Last Post: April 26th 2012, 06:29 AM
  5. Prove the probability statement
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: February 9th 2010, 03:27 PM

Search Tags


/mathhelpforum @mathhelpforum