Question

In A.P. 171, 162, 153, ………. Find first negative term.

(a) 0

(b) -2

(c) -6

(d) -9

I got this question by my school teacher while I was bunking the class.

The query is from Arithmetic Progression(A.P.) topic in portion Sequences and Series of Mathematics – Class 11

Answer 1

Right option is (d) -9

For explanation I would say: a=171 and d=162-171 = -9.

an<0

=>171+(n-1) (-9) < 0

=>180-9n < 0

=>9n > 180

=>n > 20 => n=21 for first negative term.

First negative term is 171+(20) (-9) = 171-180 = -9