Derivative of exponential function

  • Thread starter SheldonG
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  • #1
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Homework Statement


find y', [tex] y = \frac{e^x}{1+e^x}[/tex]


Homework Equations


derivative of e^x = e^x, quotient rule.


The Attempt at a Solution



The old man is back, sorry, and I don't seem to be able to enter this using the tex stuff.
This is from Kline's Calculus, page 348. I proceed as follows:

y' = [(1+e^x)(e^x)-e^x(e^x)]/(1+e^x)^2 --- the quotient rule.

Simplifying:

y' = e^x/(1+e^x)^2

However, Kline gives 1/(1+e^x).

I am at a loss. Thanks for any suggestions.

Sheldon
 
Last edited:

Answers and Replies

  • #2
mjsd
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I believe your answer is correct
 
  • #3
Gib Z
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You can check on www.calc101.com, it shows how derivatives are done. Your answer is correct, Klines books weren't very well edited >.<
 
  • #4
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Thank you both very much. Also for the calc101 link.

Sheldon
 

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