# Sigma Notation Problem

1. Jul 15, 2010

### phillyolly

Write the sum in expanded form.

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2. Jul 15, 2010

### Staff: Mentor

Is expanded form just writing it out?

3. Jul 15, 2010

### phillyolly

Previous ones, I solved them by expansion and getting a number as an answer.
This one, I think maybe just expansion?...

4. Jul 15, 2010

### Staff: Mentor

Can you post an example of a previous one where you were able to solve for a numerical answer? And is there any more information about this problem? Any definition of f(x), or delta-x?

5. Jul 15, 2010

### phillyolly

The first two are the ones I solved.

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6. Jul 15, 2010

### Staff: Mentor

Hmm. Maybe others can see something we're missing, but I'd just write it out as a sum, showing the first few terms, then some ellipses, then the nth term. Do you submit the answer to an automated checking probram online, or send it to a human for checking? If it's an automated checker, you'd need to figure out how many terms before the ellipses it expects...

7. Jul 15, 2010

### phillyolly

My instructor will check the answer...I don't think I should use ellipses in the answer. Just expansion. I have no idea what to start with.

8. Jul 15, 2010

### Staff: Mentor

This means to write the terms in the sum: f(x1)$\Delta x_1$ + f(x2)$\Delta x_2$ + and so on. Since n is not given, the usual practice is to write a few terms, then + ... + <last term>.

9. Jul 15, 2010

### Staff: Mentor

Since you don't know n, you have to use an ellipsis in your answer.

10. Jul 15, 2010

### phillyolly

Oh, I see now, thank you all a lot. You are right, I will use ellipsis.