Answer: A) 4n² - 3n
Step-by-step explanation:
The formula for determining the sum of n terms of an arithmetic sequence is expressed as
Sn = n/2[2a + (n - 1)d]
Where
n represents the number of terms in the arithmetic sequence.
d represents the common difference of the terms in the arithmetic sequence.
a represents the first term of the arithmetic sequence.
Looking at the given sequence,
a = 1
d = 9 - 1 = 17 - 9 = 8
Therefore, the formula for the sum of the first n terms in this series would be
Sn = n/2[2 × 1 + (n - 1)8]
Sn = n/2[2 + 8n - 8]
Sn = n/2[ 8n - 8 + 2]
Sn = n/2[ 8n - 6]
Sn = 4n² - 3n
