Find the differential of f(x,y)=z=xcos(xy)

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- Oct 15th 2012, 05:24 AMallstar2Need help finding a differential
Find the differential of f(x,y)=z=xcos(xy)

- Oct 16th 2012, 07:13 AMhollywoodRe: Need help finding a differential
I think you're looking for dz given that z is a function of x and y, so dz will be in terms of dx and dy. It's just the chain rule for two variables in a slightly different form:

$\displaystyle dz=\frac{\partial{z}}{\partial{x}}dx$$\displaystyle +\frac{\partial{z}}{\partial{y}}dy$

Is that what you were looking for?

- Hollywood