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Homework Help: Stuck, like a duck

  1. Jul 10, 2008 #1
    The cost function for production of a commodity is given below.
    C(x) = 369 + 21x - 0.08x^2 + 0.0006x^3

    Find the actual cost of producing the 101st item. (Round the answer to the nearest cent.)

    i know that
    c'(x) = 21-.16x+.0018x^2

    but for the life of me cannot figure out how to find the answer
  2. jcsd
  3. Jul 10, 2008 #2


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    How is "actual cost" defined?
  4. Jul 11, 2008 #3


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    How much does it cost to produce 101 items?

    How much does it cost to produce 100 items?

    So what was the cost of that 101st item?

    The derivative is irrelelvant here. This is purely and arithmetic problem.
  5. Jul 11, 2008 #4
    ive tried to just input the number and it keeps telling me that its the wrong answer ive done it every way i know how aghh
  6. Jul 11, 2008 #5
    ooo nevermind, i just got it...i feel dumb lol
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