SOLUTION: Find the number of terms and the sum of the series 7+17+27+...+107

Question 87314: Find the number of terms and the sum of the series 7+17+27+...+107
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
It appears this sequence is an arithmetic one (since we simply add 10 each time to get from term to term).
So the arithmetic sequence would be

So plug in to find out how many terms there are:

plug in

Subtract

Divide

Reduce

Since we start off at there are 11 terms

In order find the sum of an arithmetic sequence, simply use this formula

where is the first term, is the last term, and n is the number of terms

Plug in , , and

Add

Multiply

So 11 terms of this sequence adds up to 627

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