Question

Sn = 3n+1 then the common difference of ap is options a.-1 , b.3 , c.9 , d.1​

Answer 1

s1=3*1+1=4, s2=3*2+1=7

so s2-s1=7-4

difference=3

option b is correct answer

Answer 2

Answer:

Sn =3×1+1=4

Sn=3×2+1=7

Sn =7-4=3