Question

If 10th term of an AP is 97 and first term is 2 then find the ap Series and also find the sum of 15 terms

Answer 1

first term a=2

commomn diffrence=d

Tn=97

Tn=a+(n-1)d

97=2+(10-1)d

97=2+9d

9d=97-2

9d=95

d=95/9

d=10.55

Sn = n[2a + (n-1)d]/2

S15 = 10[2*2 + 14*10.55]/2

S15 = 10*75.85

s15=758.5