# Derivative of exponential function

1. Feb 13, 2007

### SheldonG

1. The problem statement, all variables and given/known data
find y', $$y = \frac{e^x}{1+e^x}$$

2. Relevant equations
derivative of e^x = e^x, quotient rule.

3. 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: Feb 13, 2007
2. Feb 13, 2007

### mjsd

3. Feb 13, 2007

### Gib Z

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. Feb 13, 2007

### SheldonG

Thank you both very much. Also for the calc101 link.

Sheldon