chain rule

jsbeckton

Junior Member
Joined
Oct 24, 2005
Messages
174
Have a question about something on my test. Here is the question:

\(\displaystyle {\rm let u = }\frac{{\rm x}}{{\rm y}} + \frac{y}{x},{\rm where }x = t^2 ,y = \cos 2t{\rm and z = e}^{{\rm - 3t}}\)

Find \(\displaystyle \frac{{du}}{{dt}}.{\rm You need not simplify}{\rm .}\)

I used \(\displaystyle \frac{{du}}{{dt}} = \frac{{\frac{{dx}}{{dt}}}}{{\frac{{dy}}{{dt}}}} + \frac{{\frac{{dy}}{{dt}}}}{{\frac{{dz}}{{dt}}}}\)



I did recieve full credit but he says that he wants me to use the chain rule instead. I know what the chain rule is but I don't know exactly what he means. Can someone just show me the format of how he wants it set up? Thanks.
 
Nevermind, I fugured it out, I guess it was just the fraction that threw me.
 
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