A simple problem pertaining to divergence

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SUMMARY

The discussion centers on the mathematical proof of the equation ∇f(r) = f'(r)R/r, where r is defined as the vector field and R = xi + yj + zk. Participants express confusion regarding the interpretation of f(r) and its dependency on the vector field R. It is clarified that f(r) is equivalent to f(√(x²+y²+z²)), emphasizing the relationship between the scalar function f and the radial distance r derived from the Cartesian coordinates.

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Homework Statement



The problem states that it is required to prove that ∇f(r)=f'(r)R/r where r is the vector field

Homework Equations


∇=(∂/∂x)i + (∂/∂y)j + (∂/∂z)k
R= xi + yj +zk
r = √(x^2+y^2+z^2)

The Attempt at a Solution



The trouble that I am having with this problem is the inability to truly comprehend what f(r) truly means⋅ Is f(r) dependent on the vector field R?
 
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Dumbledore211 said:

Homework Statement



The problem states that it is required to prove that ∇f(r)=f'(r)R/r where r is the vector field

Homework Equations


∇=(∂/∂x)i + (∂/∂y)j + (∂/∂z)k
R= xi + yj +zk
r = √(x^2+y^2+z^2)

The Attempt at a Solution



The trouble that I am having with this problem is the inability to truly comprehend what f(r) truly means⋅ Is f(r) dependent on the vector field R?
 
Is f(r) = f(x)i + f(y)j +f(z)k what being meant in the above stated problem?
 
Dumbledore211 said:

Homework Statement



The problem states that it is required to prove that ∇f(r)=f'(r)R/r where r is the vector field

Homework Equations


∇=(∂/∂x)i + (∂/∂y)j + (∂/∂z)k
R= xi + yj +zk
r = √(x^2+y^2+z^2)

The Attempt at a Solution



The trouble that I am having with this problem is the inability to truly comprehend what f(r) truly means⋅ Is f(r) dependent on the vector field R?

##f(r) = f\left(\sqrt{x^2+y^2+z^2}\right)##, because ##r## means ##\sqrt{x^2+y^2+z^2}##, as you, yourself, have written.
 

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