# Math Help - Vector Identities!

1. ## Vector Identities!

Having heaps of trouble with v.identities any help possible would be greatly appreciated.

Let F = (z,y,-x) and f = |F| <--- (magnitude F)

Use vector identities to calculate;

$
\nabla \cdot (f \nabla \times (f F))
$

2. ## Vector Identities!!

I was going to use the following identity on the part inside brackets;

$

\nabla \cdot (F \times G) = G \cdot ( \nabla \times F) - F\cdot ( \nabla \times G)

$

where $F= f \nabla$ and $G= f F$

but am not sure this is right move and wher to go from there??
cheers