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

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infinitemoesBest ResponseYou've already chosen the best response.1
no it's a n1 on the bottom of the sigma.
 10 months ago

mrbarryBest ResponseYou've already chosen the best response.1
\[\sum_{n1}^{20} (5n)\]
 10 months ago

infinitemoesBest ResponseYou've already chosen the best response.1
yes exactly like that
 10 months ago

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

mrbarryBest ResponseYou've already chosen the best response.1
This 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?
 10 months ago

infinitemoesBest ResponseYou've already chosen the best response.1
I think I got the answer. 110
 10 months ago

mrbarryBest ResponseYou've already chosen the best response.1
Let'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.
 10 months ago

mrbarryBest ResponseYou've already chosen the best response.1
You are welcome. All done? Thanks for the medal.
 10 months ago

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