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Re: Chain rule

• To: mathgroup at smc.vnet.net
• Subject: [mg24578] Re: Chain rule
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Tue, 25 Jul 2000 00:56:10 -0400 (EDT)
• Organization: Universitaet Leipzig
• References: <8lgu0g$2ip@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Hi,

Dt[2*t^2 - 1]/Dt[2t + 5]

?

Regards
  Jens

Claude wrote:
> 
> Hello,
> 
> I am just trying to solve:
> dy/dx when x = 2t + 5 and y = 2t^2 - 1.
> 
> Can it be done directly by Mathematica or do I have to solve dy/dt and
> dx/dt and finally divide dy/dt by dx/dt?
> 
> I tried posing x = 2t + 5 and y = 2t^2 - 1 and ask solve for D [y,x], but
> that does not evaluate properly (the answer is 2t).  I would have thought
> that Mathematica would have used the chain rule automatically.
> 
> Thanks for your help,