What is the sum of the first 15 terms of the arithmetic sequence -28,-24,-20? Please answer the question correctly....I will Mark you as brainlist.
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Answer:
a = -28
d = a2 - a1 = -24 + 28 = 4
n = 15
Sn = n/2 ( 2a + ( n - 1 ) d
= 15/2 ( 2 ( -28) + ( 14 ) 4)
= 15 / 2 ( -56 + 56 )
= 15/2 (0)
= 0
sum of first 15 terms is 0
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