Question

In an AP the first term is 8 and n^th term is 33 and the sum of first n terms is 123. Find n and d the common difference

Answer 1

first term=a=8

nth term=l=33

sum to first n terms=Sn=123

Sn=[n(a+l)]2

123=n(41)/2

n=6

l=a+[n-1]d

33=8+5d

d=5