Check whether -150 is a term of the AP : 11, 8, 5, 2 .......

In the A.P. : 11, 8, 5, 2 ....... First term (a) = 11 and common difference (d) = 8 - 11 = -3. Let -150 be nth term of the A.P. By formula, a n = a + (n - 1)d Substituting values we get : ⇒ -150 = 11 + (n - 1) × -3 ⇒ -150 = 11 - 3n + 3 ⇒ 3n = 150 + 11 + 3 ⇒ 3n = 164 ⇒ n = . Since, number of term cannot be in fraction. Hence, -150 cannot be the term of the A.P.