Re: Simply derivative question, Math 5.

*To*: mathgroup at smc.vnet.net*Subject*: [mg50246] Re: [mg50240] Simply derivative question, Math 5.*From*: DrBob <drbob at bigfoot.com>*Date*: Mon, 23 Aug 2004 06:34:07 -0400 (EDT)*References*: <200408220419.AAA10290@smc.vnet.net>*Reply-to*: drbob at bigfoot.com*Sender*: owner-wri-mathgroup at wolfram.com

Both these answers are correct: D[(1 + c*E^t)/(1 - c*E^t), t] (c*E^t)/(1 - c*E^t) + (c*E^t*(1 + c*E^t))/(1 - c*E^t)^2 D[(1 + c*e^t)/(1 - c*e^t), t] (c*e^t*Log[e])/(1 - c*e^t) + (c*e^t*(1 + c*e^t)*Log[e])/(1 - c*e^t)^2 Built-in constants start with capitals; hence e is undefined (unless you define it). Bobby On Sun, 22 Aug 2004 00:19:51 -0400 (EDT), Ted Kahn <tedkahn at mindspring.com> wrote: > Hello- I am trying to take the derivative of the following function: > > (1 + c*e^t)/(1 - c*e^t) > > with respect to t. > > ================ > \!\(Simplify[D[\(1 + c\ e\^t\)\/\(1 - c\ e\^t\), t]]\) > ============ > > The answer I get includes an "extra" Log[e] in the numerator. Am I not > using the program correctly or am I not understanding the answer > correctly? Other? > > thanks, -ted -- DrBob at bigfoot.com www.eclecticdreams.net

**References**:**Simply derivative question, Math 5.***From:*"Ted Kahn" <tedkahn@mindspring.com>