Question

find the sum of the first 19 terms of ap where nth term is 2n+1/3

Answer 1

put n=1,

a1=2x1+1/3

=7/3

put n=2,a2=2x2+1/3=13/3

it forms a.p=7/3,13/3....

a=7/3

d=13-7/3=6/3=2

a19=a+(19-1)d

7/3+18(2)

115/3