Find the sum of the arithmetic sequence. -1, 2, 5, 8, 11, 14, 17

andg17o7

andg17o7

Answered question

2022-09-13

Find the sum of the arithmetic sequence. -1, 2, 5, 8, 11, 14, 17

Answer & Explanation

rougertl

rougertl

Beginner2022-09-14Added 16 answers

An arithmetic sequence is of type a , a + d , a + 2 d , a + 3 d , ... .
in which first term is a and difference between a term and its preceding term is d.

n t h term of such a sequence is a + ( n - 1 ) d and sum of the series up to n terms is given by a n + n ( n - 1 ) d 2

In arithmetic sequence. {−1,2,5,8,11,14,17,.........}, a=−1 and d=3, hence of first n terms is - n + 3 n ( n - 1 ) 2 , which can be simplified to - 2 n + 3 n 2 - 3 n 2 or 3 n 2 - 5 n 2

As there are 7 terms in the series, their sum is 3 7 2 - 5 7 3 or 147 - 35 2 or 112 2 or 56.

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