Question

In an ap - 3,7,11,15....
The sum of n terms is 528. Find n and last term.

Answer 1

HEY HERE IS YOUR ANSWER...

Solution:
a = 3
d = 4
S n = 528

528 = n/2 [2a + (n-1)d]
1056 = n [6 + (n-1)4]
1056 = n [2 + 4n]
1056 = 2n + 4n^2
528 = n + 2n^2
2n^2 + n -528 = 0
2n^2 -32n +33n -528
2n (n- 16) +33 (n- 16)
(2n + 33)(n - 16)
n = 16

now, a l = a + (n-1)d
a 16 = 3+ 60
a 16 = 63.

HOPE THIS WOULD BE HELPFUL TO YOU...