Question

11, 8, 5, 2,.... In this A.P. which term is number –151?

Answer 1

The given sequence is 11, 8, 5, 2,.... –151.

\[a_n = a + \left( n - 1 \right)d\]
\[ \Rightarrow - 151 = 11 + \left( n - 1 \right)\left( - 3 \right)\]
\[ \Rightarrow - 151 = 11 - 3n + 3\]
\[ \Rightarrow - 151 = 14 - 3n\]
\[ \Rightarrow 3n = 14 + 151\]
\[ \Rightarrow 3n = 165\]
\[ \Rightarrow n = 55\]

Hence, 55^th term is number –151.