Question

an = 5n + 2

When rewriting this in summation notation to indicate the sum of the first seven terms, what do you write to the right of the Σ (capital sigma)?

Answer 1

Are you just looking for the sum of the first seven terms of your sequence? Like:
\[S_n = \sum_{i=1}^{n}a_n = \sum_{i=1}^{n}(5i+2)\]
so the sum of the first seven terms is:
\[S_7 = \sum_{i=1}^{7}(5i+2)\]
or are you saying that a_n represents the sum of the first n terms of some sequence and you are now trying to find that sequence?

Answer 2

& I am looking for what would be on the right hand side of the capita sigma...(5n+2)?

Answer 3

Im just wanting to rewrite that in summation notation but I dont know how :/

Answer 4

If I understand you correctly, you're looking for
\[a_1 + a_2 + a_3 + a_4 + a_5 + a_6 + a_7 \]where a_n = 5n+2. If that's the case, then you'll just put 5n+2 on the right side of your sigma. Just make sure you're using n as your index variable. So n=1 below your sigma and 7 above. Like this:
\[\sum_{n=1}^{7}(5n+2)\]

Answer 5

so it would be (5n+2) to the right of the sigma?

Answer 6

Yes.

Answer 7

I feel like its so easy and im making it harder than it really is

Answer 8

:) Don't over think it.

Answer 9

oh lol okay!! thanks so much

Answer 10

Any time.