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

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lemjay's profile pic

lemjay | High School Teacher | (Level 3) Senior Educator

Posted on

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.

amysor's profile pic

amysor | Student, Grade 10 | (Level 1) Valedictorian

Posted on

The pattern is +7. So the first 11 terms are 8, 15, 22, 29, 36, 43, 50, 57, 64, 71, 78. The sum of all these numbers would be 473.

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