Question

Simple dynamics proof
"Consider the central force
F= -f(r).r
(where F and r are vectors - I don't know how to denote this on here)

Prove that F is a conservative force"

I know you need to use F= - (nabla) V =0

But I'm getting myself really confused with how to write the vectors, and what V is etc...this should be a really simple question but I'm finding it difficult.

If anyone could explain it, I'd be really grateful :)