Why does the Kronecker delta interchange with itself when j equals l?

[Fredrik]

yes that's all the question wants. use quotient law to show that matrix is a 2nd order tensor.

I don't see how the quotient law can have anything to do with this.

so how do i proceed? is diagonalizing it the right way?

I have no idea. What I do know is that it's pointless to do that unless you have a way to proceed once you have found the diagonal matrix.

i think my prof also said that by the quotient law, if the matrix

(A) (scalar) = invariant, it shows that A is tensor. or something along the lines of these.

If A times a scalar is an invariant, then A is obviously invariant too. So I'm pretty sure that's not what your professor told you.

When you have a statement that you think might be useful, that may or may not be what you have been told by a professor or seen in a book, you should at least think about what it would mean if the statement is true. If you had done this here, it would have saved us both some time.

anyway, i still don't really have any idea how to solve this quesiton

I don't either, and to be honest, I still doubt that you have stated the problem correctly.

Do you have any solved examples from your book or your lecture notes that you can show me? This could at least give us some idea about how the quotient law is relevant.

 

[quietrain]

hmm its ok then , that's all the question says .

thanks for everything though, i finally understood what those indexes meant