find the sum of first 11 terms of 8,15,22,29 sequence

Expert Answers

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First, determine if the given is an arithmetic sequence. To do so, get the difference between
consecutive terms.




Since the difference between consecutive terms are the same, then 8 , 15, 22,29 is an arithmetic sequence.

So, to get the sum of the first 11 terms, the 11th term must be determine. To do so, apply the formula:


Plug-in n=11, a1=8 and d=7.




Now that the 11th term is known, use the formula:


Plug-in n=11, a1=8 and a11=78 .




Hence, the sum of the first 11 terms of the given sequence is 473.

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