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I'm very confused....

i'm suppose to find

dz/dt and dw/dt

but for some of the questions there is no w variable! so what do u put for dw/dt?! Also i have the following:

w = xy + yz^2; x = e^t; y = e^t*sint; z = e^t*cost;

so i'm trying to find dz/dt and dw/dt;

dz/dt = dz/dx * dx/dt + dz/dy * dy/dt + dz/dw * dw/dt;

but when i try dz/dx * dx/dt i need to first take the partial derivative of z with respect to x, but as you can see, z has no x variable!! so what do i do about that? THanks!

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# Homework Help: Chain rule confusion! partial derivatives

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