Question

Find the number of non-negative terms of the following sequence: 987, 932, 877,…

• A. 17
• B. 18
• C. 19
• D. 20

Answer 1

The correct option is B

18

Since 932 - 987 = -55 = 877 – 932 = common difference, d, the above sequence is an AP.

First term, a = 987; common difference, d = -55

The $n^{th}$ term, $t_n$= 987 + (n-1)(-55) = 987 – 55(n-1) < 0 (we need the first negative term)

$\Rightarrow 987<55(n-1)$

$\Rightarrow 17.94<n–1$

$\Rightarrow n>18.9$

the nearest integer is $n=19$ That is, from the ${19}^{th}$ term, the terms are all negative. So we have 18 non-negative terms.