One of the most important and exam oriented question from Chapter name- Arithmetic Progression
Class 10th
Chapter number- 9
Exercise :- 9.4
This type of question has been asked in previous years exams.
In this question we have been given an arithmetic progression. And we have to find out Which term of the AP 121, 117. 113, … is its first negative term.
CBSE DHANPAT RAI publication
Understanding CBSE Mathematics
Question 2( v)
Given that,
A.P is 121, 117, 113, ………..
First term (a) = 121,
nth term is negative i.e. an < 0,
Common difference (d) = 117 – 121 = – 4
As we know that, to find nth term in an A.P = a + (n – 1)d
121 + (n – 1) – 4 < 0
121 + 4 – 4n < 0
125 – 4n < 0
4n > 125
n > 125/4
n > 31.25
The integer which comes after 31.25 is 32.