Question

do these 2 sigmas have the same meaning?

http://puu.sh/11wcq

Answer 1

yup,same meaning,same value.

Answer 2

What's the initial value for n in the first one?

Answer 3

it's not given :S

Answer 4

are u sure the limits are 'n-2' to 5 and not 'n=2' to 5 ?

Answer 5

yes it's n-2

Answer 6

can i write like this?

Answer 7

generally the limits are not variables,so n=2 makes more sense than n-2

Answer 8

No, that doesn't work properly. Like,
\[ \sum_{n=1}^3 n = 1 + 2 + 3\]
or
\[\sum_{n=k}^3 n = k + (k+1) + (k+2) + ... + 3\]
but
\[ \sum_{n=n}^3 n = 1 + 2 + 3\] doesn't make sense.

Answer 9

so do these 2 sigmas mean the same? http://puu.sh/11wsu

Answer 10

nvm i understood

Answer 11

thx guys