This is an arithmetic progression based question from Chapter name- Arithmetic Progression

Chapter number- 9

Exercise – 9.6

In this question we have been given the arithmetic progression. Also we have to find the sum of it upto 12 terms.

CBSE DHANPAT RAI PUBLICATIONS

Understanding CBSE Mathematics

Class :- 10th

Question no 1(iv)

Given A.P. has first term(a) = 41,

Common difference(d) = 36 – 41 = -5

and number of terms(n) = 12

So, Sum of A.P. = S

_{12}= n[2a + (n – 1)d] / 2= 12[2(41) + (12 – 1)(-5)]/2

= 12[82 – 55] = 162

Hence, the sum of the first 12 terms of A.P. is 162.