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Math Help - Could be easy, but I am stumped.

  1. #1
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    Could be easy, but I am stumped.

    If f(x)=3x^2-\frac{8}{x '}\ , find the positive value of x for which f(x+1)-f(x) is least.

    I don't think I have ever seen a function with x' mixed up in there and I can't seem to even get started. Thanks in advance for any help.
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  2. #2
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    Quote Originally Posted by jabroni1212 View Post
    If f(x)=3x^2-\frac{8}{x '}\ , find the positive value of x for which f(x+1)-f(x) is least.

    I don't think I have ever seen a function with x' mixed up in there and I can't seem to even get started. Thanks in advance for any help.
    Are you sure that the prime on the x is not just a comma (not part of the formula at all)?
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  3. #3
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    I just tried it without the x' just as x, and I got the right anwer. Thanks. Wierd it really looks like an x'.
    Last edited by jabroni1212; November 14th 2007 at 07:34 AM.
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  4. #4
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by jabroni1212 View Post
    I just tried it without the x' just as x, and it doesn't seem to minimize. I am pretty sure it is as I wrote above.
    3x^2 - \frac{8}{x} has a (relative) minimum. You just have to work at it a bit.

    Otherwise, I'd just treat the x' as a constant.

    -Dan
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  5. #5
    Super Member angel.white's Avatar
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    Thats a disappointing answer, I had several theories, but was keeping my mouth shut until someone more educated than me found the correct answer. :P
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