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Math Help - Is this a valid proof?

  1. #1
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    Is this a valid proof?

    Let x be a real number and show that -[-x] is the least integer greater than or equal to x.

    Proof:
    By definition, [x] is the least integer less than or equal to x and [-x] is the least integer less than or equal to -x.
    So we have -x >= [-x]
    divide both sides by -1
    result => x <= -[-x]

    is this sufficient?pr
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  2. #2
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    Re: Is this a valid proof?

    Quote Originally Posted by evthim View Post
    By definition, [x] is the least integer less than or equal to x
    Greatest.

    Quote Originally Posted by evthim View Post
    and [-x] is the least integer less than or equal to -x.
    So we have -x >= [-x]
    divide both sides by -1
    result => x <= -[-x]
    You have not shown that -[-x] is the least integer >= x.
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