What is sum of the first 12 numbers of the series: 2 , 6, 10, 14, …?

(A) 260
(B) 268
(C) 280
(D) 288

The answer is: (D) 288
Solution
This is an arithmetic sequence with common difference of 4. The first element is 2, and total elements are 12. So, a₁ = 1, d = 3 and n = 12. So, by using the formula of nth term of an arithmetic sequence, first we will find the 12th term