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  • Dec 17, 2006, 04:39 PM
    bratzdoll3
    alg 2
    what's the x coordinate of the solution of the following system od linear equations?
    -3x-5y=-23
    2x-4y=-14

    is the answer

    a. 4
    b. 0
    c. -4
    d. -1
    e. 1

    how do you do this?
  • Dec 17, 2006, 04:51 PM
    Capuchin
    for simultaneous equations, you need to multiply up so you can get rid of a variable.

    In this case you want X, so we need to get rid of y

    If you multiply all terms in your top equation by 4 and all terms in your bottom equation by 5, you will have 2 equations both with -20y in them.

    You can then subtract the two equations, ending up with 0y and an amount of x, it's then simple algebra to solve for x.

    Let me know how you get on!
  • Dec 17, 2006, 10:11 PM
    CaptainForest
    If I have done my math correct…..

    -3x-5y=-23
    2x-4y=-14

    -5y=-23 + 3x
    -4y =-14 – 2x

    y = 4.6 - 0.6x
    y =3.5 + 0.5x

    3.5 + 0.5x = 4.6 - 0.6x
    0.6x + 0.5x = 4.6 – 3.5
    1.1x = 1.1
    x = 1
  • Dec 18, 2006, 05:27 AM
    Capuchin
    Ewww dividing.

    Multiplying up is your friend.
  • Dec 19, 2006, 12:31 AM
    CaptainForest
    -5y=-23 + 3x
    x4
    = -20y = -92 + 12x


    -4y =-14 – 2x
    X 5
    = -20y = -70 – 10x


    -92 + 12x = -70 – 10x
    12 x + 10 x = -70 + 92
    22x = 22
    x = 1

    I still get x=1
  • Dec 19, 2006, 06:10 AM
    Capuchin
    Well yes... I'm not saying you're wrong :p
  • Dec 19, 2006, 12:53 PM
    CaptainForest
    Lol

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