Answer: Calc III: Find Div(F) in Terms of r

craig16
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Homework Statement



Let r = x i + y j + z k and R = |r|. Let F = r/R^p.

find div(F) in terms of r.. i can't figure out how to express it in therms of r

Homework Equations



div(F) = the gradient added together
 
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First: express F in terms of x,y,z
Second: Compute the divergence of F by hand
Third: try to identify r in div F
 
hahaha sweet.. i figured it out. I was thinkin it was just too complicated but when you replace all the stuff with r it works out nicely.

thanks!
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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