# Is this right?

1. Dec 15, 2006

### lo2

Can this be written.

$$$\det{\textbf{A}}=a_{11}a'_{11}+a_{12}a'_{12}+\ldots+a_{1n}a'{1n}$$$

As. (Where I just use p instead of n for obvious reasons)

$$$\sum^{n}_{p=1}{a_{1p}a'_{1p}}$$$

Since.

$$$a'_{ij}=(-1)^{i+j}(\det{\textbf{A}_{ij}})$$$

And yes we are talking determinants.

Last edited by a moderator: Dec 15, 2006
2. Dec 17, 2006

### lo2

3. Dec 17, 2006

### matt grime

If you want help then write in a clear manner that people can understand, preferably in complete sentences - if people have to work hard at understanding what the question is they will tend not to bother working out what you intend.

What is a'_{rs}? What are you trying to prove?

I suspect that that doesn't matter. If all you're asking is does that summation expand to give the long hand version, then the answer is 'yes'. Just write down what the summation means.

Det has nothing to do with it as far as I can tell. But because you made a big point of saying it was abuot Det I have no idea if I've answered the question you intended to ask.

4. Dec 17, 2006

### matt grime

5. Dec 17, 2006

### lo2

I do think I made myself very clear, but well anyway thank you for the help!

6. Dec 17, 2006

### lo2

Could this post please be deleted.

7. Dec 17, 2006

### matt grime

You can delete it yourself.

If you think you were clear, can I ask what you think A_{ij} is? 'Cos we don't have a clue. And the 'since' is completely misleading. As is the sentence structure ('As.' is not a sentence, and is confusingly, given the post, like a plural form of A).

8. Dec 18, 2006

### lo2

How to do that?

9. Dec 18, 2006

### matt grime

It's too late now, but next time click on 'edit' and there is an option to delete. The edit option vanishes after some amount of time.

10. Dec 19, 2006

### lo2

But I would really like to get this post deleted.

11. Dec 19, 2006

### matt grime

Why? (added junk to meet minimum post requirement)