How many terms of the A.P.
must be taken so that their sum is 693?
Sn = 
[2a + (n – 1) d]
693 = 
[2(63) + (n – 1) (-3)]
693 = 
[126 -3n + 3]
462 = n [43 – n]
n2 – 43n + 462 = 0
n = 22 or n = 21
5
How many terms of the A.P. must be taken so that their sum is 693?
Sn = [2a + (n – 1) d]
693 = [2(63) + (n – 1) (-3)]
693 = [126 -3n + 3]
462 = n [43 – n]
n2 – 43n + 462 = 0
n = 22 or n = 21