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Homework Help: Problems with begginer level calculus

  1. Dec 29, 2011 #1
    Hello people! I have bought ''Calculus Made easy'' by Silvanus P. Thompson, I'm starting to teach myself calculus before actually taking the course. The problem discussed here will be about applying the power rule. Also, I'm not quite familiar with the use of LaTeX, so I'll try to make it as clear as possible without it.

    1. The problem statement, all variables and given/known data

    Differentiate the following : y=³√[x^(-5)]

    2. Relevant equations

    Just used the power rule really.

    3. The attempt at a solution

    y = x^(-5/3)

    dy/dx = (-5/3)x^[(-5/3)-1]

    dy/dx = (-5/3)x^(-8/3)

    and I believe I'm finished here.

    But the textbook gives a different answer : dy/dx = (-5/3)x^(-8/5)

    And I really don't see how they got (-8/5) as a power of x.

    thanks for your time.
    Last edited: Dec 29, 2011
  2. jcsd
  3. Dec 29, 2011 #2


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    It must be a typo in the book. You are right.
  4. Dec 29, 2011 #3
    thanks for the quick reply!
  5. Dec 29, 2011 #4


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    Gold Member

    Contrasting with the century it has taken to detect and correct this error - or has a new

    one been introduced in a reprint?
  6. Dec 29, 2011 #5
    ''This is a faithful reproduction of the 1914 edition of Calculus Made Easy.''

    The editor also notes that any ''non-trivial'' errors should be reported to them.

    Should I consider this error to be trivial or not?
  7. Dec 29, 2011 #6
    I would report it.
  8. Dec 29, 2011 #7


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    Yes - that is not Making Calculus Easy and other people will get stuck like you; the book is supposed to be for beginners.
  9. Dec 29, 2011 #8
    And it's a very good one at that. I recommend it to anyone with interest in the topic.
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