# Homework Help: Simple problem with tensors

1. Oct 19, 2012

### mahblah

Hi... here it is... sorry for my english...

http://sphotos-c.ak.fbcdn.net/hphotos-ak-ash4/297165_4722421629188_964469850_n.jpg [Broken]
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

Last edited by a moderator: May 6, 2017
2. Oct 19, 2012

### TSny

Hello. Looks like you replaced $A^\rho$ by $g^{\alpha\beta}A_\beta$. What happened to $\rho$ and how did $\alpha$ appear? Similarly for your indices on the partial derivative: $\sigma$ disappears while $\eta$ suddenly appears.

3. Oct 20, 2012

### mahblah

Thanks Tsny, ...but it's a simply rename of the index... i mean... i think this is not the problem..

4. Oct 20, 2012

### dextercioby

You can't rename free indices, only 'dummy' (ones summed over) ones.