Question

If 8th term of an a.P. Is 12, then the sum of first 15 terms of the a.P. Is

Answer 1

Answer:

180

Step-by-step explanation:

sum of first and last term=sum of second and second last term=...=twice sum of mid term(here 8th)

[Property of AP]

t(1)+t(15)=t(2)+t(14)=...=2*t(8)

here we get total 7 pairs and in the end we need to add t(8)

so answer is 7*twice t(8) +t(8)

7*2*12+12=180