Question

The sum of n terms of the AP 17,25,33,41,....is 627.find no of terms of the AP

Answer 1

d=a2-a1
d=25-17
d=8
a1=a=17
S=(n/2)(2a+(n-1)d)
627=(n/2)(34+(n-1)*8)
1254=n(34+8n-8)
1254=n(26+8n)
627=n(13+4n)
4n²+13n-627=0
then solve n..
n=11
therefore no. of terms in AP is 11