Results 1 to 3 of 3
Like Tree1Thanks
  • 1 Post By skeeter

Math Help - Solving for an unknown in a system of equations

  1. #1
    Member
    Joined
    Jun 2012
    From
    Australia
    Posts
    86

    Solving for an unknown in a system of equations

    I'm not sure whether there's a limit on the amount of questions we can post, especially when they're closely related, but I'm finding I'm struggling with math after 6 years out of school. Chem, funnily enough seems to be a hell of a lot easier :/.

    Anyway, the questions is as follow..

    "Determine the value of k for which the system of linear equations has infinitely many solutions. Then find all solutions corresponding to this value of k.

    3x + 4y = 12
    x + ky = 4

    Seeing as the two lines are the same line (infinite solutions), the equations should basically be equal.

    In y-intercept form, the first equation becomes y = -(3/4)x + 3.
    If x = 0, then y should equal 3, right?

    Assuming that the line is the same, then

    "x + ky = 4" becomes 3 = -(0/k) + (4/k).
    3 = (4/k)
    12 = k.


    Now, when I use this value, the equations don't work out to be parallel, so I'm going wrong somewhere, but I'm just not sure where..
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,880
    Thanks
    668

    Re: Solving for an unknown in a system of equations

    both lines are the same if all the coefficients of one equation are multiples of the other

    3x + 4y = 12

    x + ky = 4

    the first equation's coefficients are 3 times the second ... or the second equation's coefficients are 1/3 the first.

    k = 4/3
    Thanks from astuart
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Jun 2012
    From
    Australia
    Posts
    86

    Re: Solving for an unknown in a system of equations

    Thanks!

    I was miles off .
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Solving a system of 4 equations
    Posted in the Algebra Forum
    Replies: 2
    Last Post: March 7th 2012, 06:31 AM
  2. Help on Solving with System Equations
    Posted in the Algebra Forum
    Replies: 3
    Last Post: November 13th 2011, 06:16 PM
  3. system of linear equations with an unknown coefficient
    Posted in the Advanced Algebra Forum
    Replies: 6
    Last Post: September 22nd 2010, 12:30 PM
  4. Need help solving this system of equations
    Posted in the Algebra Forum
    Replies: 4
    Last Post: April 6th 2010, 03:49 PM
  5. Solving the system of equations
    Posted in the Advanced Algebra Forum
    Replies: 1
    Last Post: March 25th 2009, 06:50 PM

Search Tags


/mathhelpforum @mathhelpforum