Question

1,7,13,.... is a arithmetic sequence. find the sum of consecutive 22 term of this sequence?​

Answer 1

n= 22 , a= 1 , d= 7-1= 6 , Sn =?

Sn = n/2{2a+(n-1)d}

= 22/2 {2+21×6}

= 11×128

= 1408