Question

f=1,d=1, in that A.P. sum of some terms is 100.how many terms in that A.P?

Answer 1

f=1
d=1
sum=100
sn=n/2[2f+(n-1)d]
100=n/2[2+n-1]
200=n(1+n)
n²+n=200
14*15=200
n=14