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Math Help - I need proof...

  1. #1
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    I need proof...

    I need proof for the problem:
    What are the values of x and y?
    50x+100y=900
    x+1.5y=15.5

    The answer is x=8 and 5=y. I simply guessed and my teacher requires proof.
    The proof cannot be a guess and check method.
    Last edited by ceasar_19134; October 27th 2006 at 11:30 AM. Reason: ThePerfectHacker
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  2. #2
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    Quote Originally Posted by ceasar_19134 View Post
    I need proof for the problem:
    What are the values of x and y?
    50x+100y=900
    x+1.5y=15.5

    The answer is x=8 and 5=y. I simply guessed and my teacher requires proof.
    That is proof!
    If it works that is your proof.
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  3. #3
    Grand Panjandrum
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    Quote Originally Posted by ceasar_19134 View Post
    I need proof for the problem:
    What are the values of x and y?
    50x+100y=900
    x+1.5y=15.5

    The answer is x=8 and 5=y. I simply guessed and my teacher requires proof.
    The proof cannot be a guess and check method.
    Multiply the second equation by 50 to get the pair of equations:

    50x+100y=900
    50x+75y=775

    Now subtract to get:

    25y=125.

    And I expect you can take it from there.

    RonL
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  4. #4
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by ThePerfectHacker View Post
    That is proof!
    If it works that is your proof.
    Sounds like a rather "Physics-y" proof if you ask me.

    -Dan
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  5. #5
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    Quote Originally Posted by topsquark View Post
    Sounds like a rather "Physics-y" proof if you ask me.

    -Dan
    Why?

    The reason why you use a technique or method to solve a problem is because you do not want to guess through uncountably many possibilities
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