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Homework Help: Area Under 3 Curves PtII

  1. Feb 24, 2006 #1
    hi! Thanks for the advice, I managed to find the intersection points, but I seem to have run into a problem.
    I set up the integral as follows:

    (4-x^2) (for 1 to 2) + (4 - 1/x) (for 1/4 to 1)
    this worked out to
    ((8-8/3) - (4 - 1/3)) + (4 - (1 - ln1/4))
    (16/3 - 11/3) + (3 + ln1/4)
    5/3 + 3 + ln 1/4
    = 14/3 + ln1/4

    but the answer at the back says that the correct response is
    14/3 - ln4... What did I do wrong?
    Thanks so much,
    heather
     
  2. jcsd
  3. Feb 24, 2006 #2
    The (4-x^2) integral gives you the total area in that interval. However, the 1/x curve "intersects" the area. Therefore, you must subtract that part from the first integral. If you plot the curves, you will see what I am talking about.
     
  4. Feb 24, 2006 #3
    By the way, there is no need to start a second thread about the same problem. You could have just as well continued in your first thread.
     
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