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Homework Help: Surface area of Revolution

  1. Oct 15, 2013 #1
    1. The problem statement, all variables and given/known data
    I want the surface area of Revolution about x from [-2,2] of y = |x|
    So I want to know if I can take it x from [0,2] and just multiply this result by 2?

    2. Relevant equations

    3. The attempt at a solution

    Set up
    dy/dx = (5/(2√x))

    S = 2 ∏ ∫ 5x^1/2(√ 1 +((5/(2√x))^2)

    from x = 0 , to x = 2. Then multiply this result by 2? Is this OK to do?
  2. jcsd
  3. Oct 15, 2013 #2


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    Science Advisor
    Homework Helper

    Yes, the function y=|x| is symmetric around the y-axis, so you can double the result from [0,2]. But why do you think dy/dx = (5/(2√x))??
  4. Oct 15, 2013 #3
    Because I;m tired lol and looked off the wrong sheet. My bad. I had this problem done I just didn't know if I could do what I said I didn't see why not though. Thanks,
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