Chain rule

*To*: mathgroup at smc.vnet.net*Subject*: [mg24562] Chain rule*From*: "Claude" <fran_claude at hotmail.com>*Date*: Mon, 24 Jul 2000 03:04:46 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

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,