Question

If first of an A.P. is 2 and the common difference is 4, then the sum of 400 terms​

Answer 1

Answer:

320000

Step-by-step explanation:

a = 2, d = 4, n = 400

Now,

$Sn = \frac{n[2a+(n-1)d]}{2} \\ = \frac{400[2*2+(400-1)*4]}{2} \\ = \frac{400*1600}{2} \\ = 320000$