# chain rule (partial derivatives)Watch

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#1
use the chain rule to find dw/dt

w=xe^y/2 , x= t^2 , y= 1-t , z=1+2t

any help would be great thanks
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13 years ago
#2
Are you sure you've quoted the question right? It seems to me that dx/dt = 2t.
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#3
i corrected it thanks ...
0
13 years ago
#4
(Original post by david cool)
use the chain rule to find dw/dt

w=xe^y/2 , x= t^2 , y= 1-t , z=1+2t

any help would be great thanks
I'm not sure whether your expression for w is xe^(y/2) or x(e^y)/2. I'll do the working for the latter and you can easily change it if it's the other one.
pw/pt=(pw/px)(px/pt)+(pw/py)(py/pt)
=(e^y / 2)(2t)+(xe^y / 2)(-1)
=te^(1-t)-(1/2)(t^2)e^(1-t)
=(e^(1-t))[t-0.5t^2])
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