# Vector Calculus Identity

1. Sep 21, 2011

### Rubik

I am trying to figure out a proof for this identity

$\nabla$(f/g) = (1/g2) (g$\nabla$f - f$\nabla$g)

Any ideas?

2. Sep 21, 2011

### mathman

It looks like a vector version of the derivative of a quotient. Look at each component separately.

3. Sep 21, 2011

### techmologist

The quotient rule for ordinary derivatives:

(f/g)' = (gf' - fg')/g2

works for partial derivatives, too.

4. Sep 21, 2011

### Rubik

Thanks so much I got it :)