The arithmetic sequence a_ia i a, start subscript, i, end subscript is defined by the formula: a_1 = 15a 1 =15a, start subscript, 1, end subscript, equals, 15 a_i = a_{i - 1} -7a i =a i−1 −7a, start subscript, i, end subscript, equals, a, start subscript, i, minus, 1, end subscript, minus, 7 Find the sum of the first 660660660 terms in the sequence.

-1,512,390

Step-by-step explanation:

Given

a1 = 15

Let us generate the first three terms of the sequence

For

Hence the first three terms ae 15, 8, 1...

This sequence forms an arithmetic progression with;

first term a = 15

common difference d = 8 - 15 = - -8 = -7

n is the number of terms = 660 (since we are looking for the sum of the first 660 terms)

Using the formula;

Substitute the given values;

Hence the sum of the first 660 terms of the sequence is  -1,512,390

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step-by-step explanation:

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