This is the basic and conceptual question from Chapter name- Arithmetic Progression
Chapter number- 9
Exercise 9.4
In this question we have been given an arithmetic progression. And we have to find out no of terms in this AP
CBSE DHANPAT RAI publications
Class:- 10th
Understanding CBSE Mathematics
Question 4(iv)
Given that,
A.P. 18, 15½, 13, …., -47
where, a = 7 and d = 15½ – 18 = 5/2,
As we know that, to find nth term in an A.P = a + (n – 1)d
a + (n – 1)d = 43
18 + (n – 1)(-5/2) = -47
18 – 5n/2 + 5/2 = -47
36 – 5n + 5 = -94
5n = 94 + 36 + 5
5n = 135
n = 27
Hence, there are 27 terms in the given A.P.