Question

find the sum of the first 15th term of an ap are thematic series 3 + 8 + 11 + 3 + 50 and using suitable formula​

Answer 1

Answer:

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

a=3

d=8-3=5

n=15

sn = 15/2(2*3+(15-1)5)

15/2(6+70)

15/2*76

15*38

=570