Question

2+3+5+9+8+15+11+21+....... So find (2n+1)

Answer 1

n=21
d= 4
a=2
a(n-1)d
n= 2(n-1)4=21
angel change
4×2-21(n-1)
21-8(n-1)
(n-1)=13

(13×2+1)=27