# Help with tensor homework

1. Apr 26, 2009

### latentcorpse

if $\epsilon_{ijk} P_{kj}=0$ how do we show $P_{ij}=P_{ji}$?

2. Apr 26, 2009

### dx

Re: tensors

Expand out the LHS for each i.

3. Apr 26, 2009

### latentcorpse

Re: tensors

do you mean just substitute in numbers and see what happens because that works - i was just wondering if i could do it without explicitly using numbers (i.e. all of it in index notation).

4. Apr 26, 2009

### dx

Re: tensors

For i = j, clearly Aij = Aji, so you only need to check the cases in which i ≠ j.

For example, setting i = 1 in εijkAkj = 0, you get ε123A32 + ε132A23 = A32 - A23 = 0 ⇒ A32 = A23.

You just need to do the same with i = 2 and i = 3.