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infinitemoes
 one year ago
Please help! What is the sum of the series? 20 on top and n1 on the bottom of ∑(5n)
infinitemoes
 one year ago
Please help! What is the sum of the series? 20 on top and n1 on the bottom of ∑(5n)

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infinitemoes
 one year ago
Best ResponseYou've already chosen the best response.1no it's a n1 on the bottom of the sigma.

mrbarry
 one year ago
Best ResponseYou've already chosen the best response.1\[\sum_{n1}^{20} (5n)\]

infinitemoes
 one year ago
Best ResponseYou've already chosen the best response.1yes exactly like that

mrbarry
 one year ago
Best ResponseYou've already chosen the best response.1It should be n=1 I am certain. If we did this "manually" we would have 4 + 3 + 2 + ... Right?

mrbarry
 one year ago
Best ResponseYou've already chosen the best response.1This is an arithmetic sequence b/c we are adding 1 over and over. There is a formula to solve this, Arithmetic Series Formula. Do you know it?

infinitemoes
 one year ago
Best ResponseYou've already chosen the best response.1I think I got the answer. 110

mrbarry
 one year ago
Best ResponseYou've already chosen the best response.1Let's see. The formula says: 1/2 the number of items times (first term + last term) 1/2 (20) (4 + 15) 10 (11) Good job.

mrbarry
 one year ago
Best ResponseYou've already chosen the best response.1You are welcome. All done? Thanks for the medal.

infinitemoes
 one year ago
Best ResponseYou've already chosen the best response.1Well I do have a couple more questions, but I'm gonna post them separate to this post.
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