Question

if n term of an ap is 2n+1 what is the sum of first three terms of an ap​

Answer 1

hope this will help you

Answer 2

Step-by-step explanation:

tn =a+(n-1)d is general formula of ap comparing this to 2n+1 we will get d=2 and a=3 so sum of first three terms is 3/2{2×3+(3-1)2}=3/2×10=15 it's formula of sum of nth term of ap.