(i) 11, 8, 5, 2, .... is an A.P.
a = 11 d = 8 - 11 = -3
150th term = a150 = a + (150 - 1)d
= 11 + 149 x -3
= 11 - 447 = -436
(ii) a3 = 12, an = a50 = 736
\(\therefore\) a + 2d = 12---(1)
a + 49d = 736----(2)
⇒ 47d = 724 (By (2) - (1))
⇒ d = 724/47 ⇒ a = 12 - 2d
= 12 - \(\frac{724\times2}{47}\) = \(\frac{564-1448}{47}\)
= \(\frac{-448}{47}\)
Let nth term be zero
\(\therefore\) a +(n -1)d = 0
⇒ \(\frac{-884}{47}+(n-1)\frac{724}{47}=0\)
⇒ 724(n - 1) = 884
⇒ n -1 = 884/724
⇒ n = 1608/724
which is not a whole number
\(\therefore\) No term of A.P. will be zero.