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Homework Help: Length of a Curve(integrals)

  1. Mar 27, 2009 #1
    1. The problem statement, all variables and given/known data

    How can we found the length of the curve:
    [tex]f(x) = \frac {1}{12}(x - 48)\sqrt x[/tex]

    where [tex]x\ge0[/tex] and the vertical line x=48.

    2. Relevant equations

    3. The attempt at a solution
    I tried to use the formula [tex]L=\int^{48}_{0}\sqrt {1 + \ [f'(x)]^2} dx[/tex]
    But I think that there is a problem where x=0 because the first derivative is:
    [tex]f'(x) = \frac {(x - 16) \sqrt {x}}{8x}[/tex] and because x is in the denominator cannot take the value 0.

    How can solve this issue??
    Any ideas??
    Thanks anyone in advance.
  2. jcsd
  3. Mar 27, 2009 #2


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    Gold Member

    What is the final integral? Do you know what the function looks like after the integral has been performed?
  4. Mar 27, 2009 #3
    No I don't
  5. Mar 27, 2009 #4


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    Gold Member

    You should try performing the integral before you ask whether or not there is division by zero. Perhaps there may be division by zero, in that case you will have to use the improper integral method (limit) to find out whether it converges or diverges at that point.
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