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Math Help - [SOLVED] Simultaneous equations

  1. #1
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    [SOLVED] Simultaneous equations

    Solve 2^x=14-2x simultaneously.
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    MHF Contributor red_dog's Avatar
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    A solution is x=3.

    Let f(x)=2^x, \ g(x)=14-2x

    f(x) is strictly increasing, and g(x) is strictly decreasing, so the solution is unique.
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by requal View Post
    Solve 2^x=14-2x simultaneously.
    this is not really simultaneous equation problem. you need more than one equation for that.

    note that on the right, if you make x too big (bigger than 7), you get a negative answer. the left side is always positive, so you want to try x values that are less than 7. there is one positive solution (meaning you would try integer values for x). trial and error can find it
    Last edited by Jhevon; February 1st 2009 at 12:11 AM. Reason: thanks Moo :p
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  4. #4
    Moo
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    Quote Originally Posted by Jhevon View Post
    this is not really simultaneous equation problem. you need more than one equation for that.

    note that on the right, if you make x too big (bigger than 7), you get a negative answer. the right side is always positive, so you want to try x values that are less than 7. there is one positive solution (meaning you would try integer values for x). trial and error can find it
    Got any problem with left & right ?




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