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Sigma notation C2

Hey guys

I just can't get my head round sigma notation for series' in C2:P
What part of a series do the letters around it represent?? Any help would be much appreciated :smile:

Reply 1

The H

The bottom number is the first value of n. So if the sum was being calculated from the first term, n would be 1.
The top number is the last value of n, so you are calculating the sum from the n value below sigma to the value above it.
And on the right is just the expression for the next term in the series

Reply 2

mike256

The bottom of the sigma has something like k = 1 (but it could be any letter), and the top of the sigma has a number such as 10. This means you find the sum of the expression to the right of the sigma, when k = 1, 2, 3,... up to the number on the top of the sigma.

For example,

\displaystyle \sum_{k=1}^{10} (2k + 1)

would mean you sum up the results of substituting in k = 1 up to 10 into the expression on the right, which means

(2 x 1 + 1) + (2 x 2 + 1) + (2 x 3 + 1) + ... + (2 x 10 + 1)