Expanded Form of Sigma Notation Problem

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phillyolly
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Write the sum in expanded form.

I don't know where to start with...
 
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  • Sigma notation sum with index i from 1 to n of f(x_i) times delta x_i, followed by an equals sign with nothing after it.
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phillyolly said:
Write the sum in expanded form.

I don't know where to start with...

Is expanded form just writing it out?
 
Previous ones, I solved them by expansion and getting a number as an answer.
This one, I think maybe just expansion?...
 
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?
 
The first two are the ones I solved.

The book has no more information, just this one.
 
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  • Three sigma-notation sums: the sum from i=1 to 6 of 1/(i+1) expanded as 1/(1+1) + 1/(2+1) + ... + 1/(6+1) = 1.592; the sum from i=4 to 6 of i cubed equals 4^3 + 5^3 + 6^3 = 405; and the sum from i=1 to n of f(x_i) times delta x_i, left unfinished.
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phillyolly said:
The first two are the ones I solved.

The book has no more information, just this one.

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...
 
berkeman said:
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...

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.
 
phillyolly said:
Write the sum in expanded form.

I don't know where to start with...
This means to write the terms in the sum: f(x1)[itex]\Delta x_1[/itex] + f(x2)[itex]\Delta x_2[/itex] + and so on. Since n is not given, the usual practice is to write a few terms, then + ... + <last term>.
 
phillyolly said:
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.
Since you don't know n, you have to use an ellipsis in your answer.
 
Mark44 said:
This means to write the terms in the sum: f(x1)[itex]\Delta x_1[/itex] + f(x2)[itex]\Delta x_2[/itex] + and so on. Since n is not given, the usual practice is to write a few terms, then + ... + <last term>.

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