Find the sum of the following APs:
, 
, 
….., to 11 terms
In the above series
First term (a) = 
Common different (d) = n2 – n1 = 
- 
= 
No. Of terms (n) = 11
The sum of the series is given by Sn = 
[2a + (n-1) d]
= 
[2×(
) + (11-1)
)]
= 
[
+ 
]
= 
1