Question

Is 51 a term of 5, 8, 11, 14, ...,?

Answer 1

Here, a = 5, d = (8 − 5) = 3
Let the n^th term of the given AP be 51.
Then T_n = 51
⇒ a + (n − 1)d = 51
​⇒ 5 + (n − 1) ⨯ ​3 = 51
⇒ 3n = 49
⇒ n = $16\frac{1}{3}$, but n cannot be a fraction.
∴ 51 is not a term of the given AP.