The nth term Tn = n - 12 illustrates an arithmetic progression
The sum of the first 25 terms is 25
How to determine the sum of the terms?
The nth term is given as:
Tn = n - 12
Calculate the first term
a = 1 - 12
a = -11
Calculate the second term
T2 = 2 - 12
T2 = -10
Calculate the common difference (d)
d = T2 - a
d = -10 + 11
d = 1
The sum of n terms is then calculated as:
Sn = n/2(2a + (n - 1) * d)
So, we have:
S25 = 25/2(-2 * 11 + (25 - 1) * 1)
Evaluate
S25 = 25
Hence, the sum of the first 25 terms is 25
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