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Math Help - word problem and interval notation

  1. #1
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    word problem and interval notation

    I never liked wp's

    the perimeter of a standard rug is 44ft the length is 2ft longer than the width find the dimensions width and length anyone please?


    interval notation of the set {xl -2 > x > 6}

    is it (-6 -2) ?
    Last edited by rj2001; April 14th 2007 at 08:35 PM. Reason: adding
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by rj2001 View Post
    I never liked wp's

    the perimeter of a standard rug is 44ft the length is 2ft longer than the width find the dimensions width and length anyone please?


    interval notation of the set {xl -2 > x > 6}

    is it (-6 -2) ?
    Are you sure this is the right question? to have an interval for such a question, we need an inequality. there's no inequality here.

    let width = x
    => length = x + 2
    => Perimeter = 2x + 2(x + 2) = 44
    => 2x + 2x + 4 = 44
    => 4x + 4 = 44
    => 4x = 40
    => x = 10

    so the width is 10 and the length is 12

    so the rug is a 10 x 12 rug

    EDIT: oh, the interval thing is for the second question, ok i'll do that...what is xl?
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  3. #3
    is up to his old tricks again! Jhevon's Avatar
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    ok, so {x| -2> x > 6} makes no sense. what you are actually saying is x is less than -2 but greater than 6. I think it should be {x| -2 < x < 6}, that is, x is greater than -2 but less than 6.

    so in interval notation that would be (-2,6). we use parenthesis as oppsosed to square brackets since x cannot be equal to either of the values at the end points.
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  4. #4
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    Hello, rj2001!

    Is that interval problem stated correctly?
    If it is, it's not the way we should write it.


    interval notation of the set {x l -2 > x > 6}

    It says: x > 6 . (x is greater than 6)
    . . and: -2 > x . (x is less than -2)

    This is clearly impossible; a number cannot be greater than 6 and less than -2.


    The intent could have been: .x < -2 .or .x > 6

    And the interval would be: .(-∞, -2) U (6, ∞)

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  5. #5
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    hi yeah sorry for not making it clear that was 2 problems in one post

    but yeah the second one is on our online homework (mymathlab) multiple choice

    Write interval notation for the set

    { x l -2 > x >-6 } the l = absolute value bar? but just one no close

    answers are
    (-6,-2)
    [-6,-2]
    [-6,-2)
    (-6,-2]

    this is a review from a chapter wayy back and I think he read it x is such that? something dunno if that will help
    Last edited by rj2001; April 15th 2007 at 07:17 AM. Reason: adding
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  6. #6
    Bar0n janvdl's Avatar
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    x is between -2 and -6, but neither of the two numbers is included.
    Which means that x is not equal to either -2 or -6, but lies between them.

    For the rug:
    Perimeter = 2L + 2B
    But L = (x + 2)
    B = (x)

    44 = 2(x + 2) + 2(x)
    44 = 4x + 4
    x = 10

    Thus B = 10
    And L = 10 + 2 = 12
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