Question

The 8th term of an A.P is zero. Prove that its 38th term is equal to thrice the 18th term

Answer 1

8th term means a+7d i.e a+7d=0 or a= -7d 38th term=a+37d=-7d+37d=30d. 18th term =a+17d=-7d+17d=10d

Answer 2

8th term=a+7d
a=-7d
18th term=a+17d
=-7d+17d
=10d
38th term=a+37d
=-7d+37d
=-30d
as 30d is thrice of 10d
hence proved