Question

Find the sum of an A.P seventeen terms whose middle term is 5

Answer 1

Answer:

17 terms, the middle term is term 9

so

a + 8d = 5 -----> a = 5-8d

sum(17) = (17/2)(2a + 16d)

= (17/2)(10-16d + 16d)

= (17/2)(10)

= 85

answer 85