Question

for an a.p the first and the last term are 13 and 216 respectively . common difference 7 how many terms are there in the a.p ? find the sum of all the term

Answer 1

hey dear here is your answer..
a=13
Tn=216
d=7
n=?
Sn=?

d=(Tn -T1)/(n-1)

7=(216-13)/(n-1)
7n-7=203
n=30

Sn =n/2(a+Tn)
= 15(13+216)
= 15×229
=3435
HOPE OT HELPS

Answer 2

a = 13
& l= 216

216 = 13 + (n-1) 7
(n-1) 7 = 203
n-1 = 29
n = 30

sn = n/2(a+l)
= 15(13+216)
= 15×229
= 3435