The derivative with respect to what? What variables are dependent on other variables? Are you taking partial derivatives?
What method is used?
Can the product rule be extended for a third dimension.
I know that for cosx.siny you can use dy/dx=u*(dv/dx) + v*(du/dx)
But what can be used to differentiate sinx.cosy.cosz? can the above rule be extended for a third dimension?
Thanks for your help
What Ackbeet said!
Now as for the extension, yes, it can be extended to any finite number of products. Here is an example of how to do it. Let f,g and h be functions of a variable, say x. Then we can use the product rule twice to obtain the following:
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