# Discrete Math Proof

1. Oct 18, 2012

### Bashyboy

1. The problem statement, all variables and given/known data
I attached the problem as a file.

2. Relevant equations

3. The attempt at a solution
I get stuck on how to properly represent the summation. How does k find it's way as one of the sub-scripts?

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Last edited: Oct 18, 2012
2. Oct 18, 2012

### HallsofIvy

Your post makes no sense and there is no attachment.

3. Oct 18, 2012

### Bashyboy

I am so sorry, I'll fix that.

4. Oct 18, 2012

### HallsofIvy

Okay, you have BTAT. Now, what is (AB)T?

5. Oct 19, 2012

### Bashyboy

So,

$AB = \sum_k a_{ki}b_{jk}$

$(AB)^t = \sum_k a_{ki} b_{jk} = \sum_k b_{jk} a_{ki} = B^tA^t$

Does that look correct?

Last edited: Oct 19, 2012
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