Results 1 to 5 of 5

Math Help - Linear equations problem

  1. #1
    Newbie
    Joined
    Oct 2012
    From
    Boston
    Posts
    4

    Linear equations problem

    Hi all, I'm working on this problem and for some reason, seem to keep getting stuck in a loop of wrong answers.

    So we're given:
    x + y = 1, 0.7x + 0.2y = x, and 0.3x + 0.8y = y

    I'm instructed to multiply the terms by 10 to simplify, and to combine the like terms in order to solve:

    ___x + 2y = 0

    and

    ___x - 2y = 0

    The answer is -3 and 3, but I don't know how to arrive at that.

    Any help will be much appreciated!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member kjchauhan's Avatar
    Joined
    Nov 2009
    Posts
    137
    Thanks
    2

    Re: Linear equations problem

    Multiplying the 2nd equation by 10, we get,
    7x + 2y = 10x
    \therefore 7x-10x+2y=0
    \therefore -3x+2y=0
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Oct 2012
    From
    Boston
    Posts
    4

    Re: Linear equations problem

    Beautiful! Such a simple thing; I didn't see how easy this was. Yet another example of how math is a great exercise in attention to detail. Thanks!
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Sep 2012
    From
    Canada
    Posts
    19

    Re: Linear equations problem

    If you want a more "normalized" way of doing it, in case you can't see it like that, check this image.
    Linear equations problem-2012-11-28-19.18.05.jpg
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Oct 2012
    From
    Boston
    Posts
    4

    Re: Linear equations problem

    That's also very helpful, thanks Richard! I saw it right away with KJ's post-- my mistake was in not also multiplying the right side of the two equations (x, and y, respectively) when multiplying the left side by 10.

    This is my first post on here asking for help and I am very pleased and impressed with this, thanks so much for the quick replies! I'll try to do the same where I can.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Help with Linear Equations Problem
    Posted in the Algebra Forum
    Replies: 2
    Last Post: January 9th 2011, 03:28 PM
  2. Linear Equations Problem (Please Help!!!)
    Posted in the Algebra Forum
    Replies: 2
    Last Post: January 9th 2011, 07:11 AM
  3. the problem of linear equations
    Posted in the Advanced Algebra Forum
    Replies: 3
    Last Post: July 28th 2010, 01:44 AM
  4. Two linear equations problem.
    Posted in the Algebra Forum
    Replies: 3
    Last Post: March 16th 2010, 05:24 AM
  5. Graphing Linear Equations Problem
    Posted in the Algebra Forum
    Replies: 10
    Last Post: December 18th 2008, 08:11 AM

Search Tags


/mathhelpforum @mathhelpforum