Question

Which term of AP 72, 68, 64, 60, ... is 0?

Answer 1

In the given AP, first term, a = 72 and common difference, d = (68 – 72) = –4.

Let its n^th term be 0.

Then, T_n = 0

⇒ a + (n – 1) d = 0

⇒ 72 + (n – 1) × (–4) = 0

⇒ 76 – 4n = 0

⇒ 4n = 76 

⇒ n = 19 

Hence, the 19^th term of the given AP is 0.