Results 1 to 5 of 5

Math Help - Easy? algebra problem

  1. #1
    Junior Member
    Joined
    Jan 2013
    From
    Chicago
    Posts
    27

    Easy? algebra problem

    y^2 - 2xy - 16 = 0

    y = ??

    Can't seem to express y in terms of x
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Nov 2010
    Posts
    1,874
    Thanks
    735

    Re: Easy? algebra problem

    y^2 - 2xy - 16 = y^2 - 2xy + (x^2 - x^2) - 16
    = (y^2 - 2xy + x^2) - x^2 - 16
    = (y-x)^2 - x^2 - 16 = 0
    Adding x^2+16 to both sides, you get:
    (y-x)^2 = x^2 + 16
    Taking the square root of both sides, you get:
    y-x = +/- SQRT(x^2 + 16)
    Adding x to both sides, you get:
    y = x +/- SQRT(x^2+16)
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,738
    Thanks
    644

    Re: Easy? algebra problem

    Hello, kjtruitt!

    \text{Solve for }y\!:\;\;y^2 - 2xy - 16 \:=\: 0

    Have you been taught the Quadratic Formula?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member
    Joined
    Jan 2013
    From
    Chicago
    Posts
    27

    Re: Easy? algebra problem

    Yes. The text uses it here but I was still confused by the reversal of the common variables and also the way x figures into the quadratic. Before I worked it though, I decided I ought to be able to manipulate the equation algebraicly so that y is expressed in terms of x...the first answer here does that nicely.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Jan 2013
    From
    Chicago
    Posts
    27

    Re: Easy? algebra problem

    Thanks this is just what I was looking for.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Easy Algebra Question
    Posted in the Algebra Forum
    Replies: 3
    Last Post: July 8th 2013, 06:32 AM
  2. Replies: 2
    Last Post: February 9th 2013, 08:59 PM
  3. Algebra Word Problem Easy
    Posted in the Algebra Forum
    Replies: 3
    Last Post: August 28th 2010, 02:08 PM
  4. Easy algebra question need help!!!
    Posted in the Algebra Forum
    Replies: 3
    Last Post: June 18th 2009, 06:01 AM
  5. Easy algebra
    Posted in the Algebra Forum
    Replies: 1
    Last Post: March 4th 2008, 03:19 AM

Search Tags


/mathhelpforum @mathhelpforum