How to Find Sum of First n Terms When nth Term is Given ?
A series whose terms are in Arithmetic progression is called Arithmetic series.
To find sum of arithmetic series, we use one of the formulas given below.
Sn = (n/2) [a + l]
Sn = (n/2) [2a + (n - 1)d]
a = first term,
n = number of terms of the series,
d = common difference and l = last term