# Homework Help: Help with Beginner Index Notation

1. Dec 20, 2009

### fttteotd

Okay, so I'm learning some basic index notation, and I have a few questions...
1. The problem statement, all variables and given/known data
f= scalar field
F = vector field

so, we are supposed to show that curl(fF) = fcurl(F) + ($$\nabla$$f) x F

3. The attempt at a solution

curl(fF) = [$$\nabla$$ x (fF))]$$_{k}$$ = $$\in$$$$_{ijk}$$(f$$\partial$$$$_{i}$$F$$_{j}$$ + F$$_{j}$$$$\partial$$$$_{i}$$f)

any help??

(all the superscripts are supposed to be subscripts, i dunno)

2. Dec 20, 2009

### tiny-tim

Welcome to PF!

Hi fttteotd! Welcome to PF!

(have a curly d: ∂ and a nabla: ∇ and an epsilon: ε and use itex rather than tex in the middle of a line )

[∇ x (fF)]i = εijkj(fFk) …

and now use the chain rule!