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Homework Help: Is this derivative correct?

  1. Oct 21, 2012 #1
    1. The problem statement, all variables and given/known data

    Find the derivative of y=x1/x

    2. Relevant equations

    Chain rule and logarithmic differentiation.

    3. The attempt at a solution


    Sorry for all the brackets, and if they are not correct :$
  2. jcsd
  3. Oct 21, 2012 #2
    In your 6th line I think I see a mistake you're using the product rule it seems? In the second part what did you take the derivative of?
  4. Oct 21, 2012 #3
    Should it read:

  5. Oct 21, 2012 #4
    close shouldn't the derivative of x^-1 be -1*x^-2??
  6. Oct 21, 2012 #5
  7. Oct 21, 2012 #6
    Looks good to me. Just plug in y like you did in the last step of the 1st post and you're golden.
  8. Oct 21, 2012 #7
    Thanks a bunch :)
  9. Oct 22, 2012 #8
    You have a problem with parentheses, but more importantly, lines 4 and 5 are very wrong.

    You cannot differentiate the LHS and still equate it with the RHS without differentiating the RHS also.

    However you still got there - as long as you correct your parentheses.
    Last edited: Oct 22, 2012
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