We now ask, how can we apply the product rule to evaluating
these things?
The
or "del" operator and the dot and cross product
are all linear, and each partial derivative obeys the product
rule. We now ask: what is
Applying the product rule and linearity we get
or "del" operator and the dot and cross product
are all linear, and each partial derivative obeys the product
rule. We now ask: what is 
