Home/ Questions/Q 7511
In Process
Adv
deepaksoni
  • 0
Guru
Asked: 2021-06-29T10:08:18+05:30 In:

Question 5. Find the sum of first 15 terms of each of the following sequences having nth term as(iii) xn = 6 – n

  • 0

This is the basic and conceptual question from Chapter name- Arithmetic Progression
Chapter number- 9
Exercise 9.6

In this question we have been given an arithmetic progression having nth term as xn = 6 – n

And we have to find its sum of first 15 terms.

CBSE DHANPAT RAI publications
Class:- 10th
Solutions of CBSE Mathematics
Question 5(iii)

arithmetic progressionsrd sharma class 10th
Share

    1 Answer

    1. Guru

      Given A.P. has nth term, an = 6 – n

      and number of terms(n) = 15

      So, an = 6 – n = -9

      On putting n = 1, we get a, first term of the A.P.,

      a = 6 – 1 = 5

      S15 = n[a + an]/2

      = 15(5 – 9)/2 = 15 x (-2) = -30

      Hence, the sum of the first 15 terms of given A.P. is -30.

      • 0
    Leave an answer

    Leave an answer

    Browse

    Choose from here the video type.

    Put Video ID here: https://www.youtube.com/watch?v=sdUUx5FdySs Ex: "sdUUx5FdySs".

    Captcha Click on image to update the captcha.

    Related Questions

    Adv