Question

find the maximum sum of the a.p. 30,27,24,21

Answer 1

Answer:

a=30,d=27-30,n=?

= -3

an=a+(n-1)d

= 30+(n-1)-3

-30=-3(n-1)

n-1=-30/-3

n-1=10

then , n= 11

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

11/2[2×30+(11-1)-3]

11/2 [30]

11×15

165