Question

How many terms are there in the AP 41, 38, 35,...., 8 ?

Answer 1

In the given AP, a = 41 and d = (38 - 41) = -3
Suppose that there are n terms in the given AP.
Then T_n = 8
⇒ a + (n - 1) d = 8
⇒ 41 + (n - 1) ⨯ (-3) = 8
⇒ 44 - 3n = 8
⇒ 3n = 36
⇒ n = 12
Hence, there are 12 terms in the given AP.