Adv
Deepak Bora
  • -2
Newbie

If the nth term of an AP is (4n+1) find the sum of the first 15 terms of the AP. Also find the sum of its n terms.

  • -2

This is the Important question based on Arithmetic progression Chapter of R.S Aggarwal book for ICSE & CBSE Board.
Here the nth term of AP is given
you have to find the
(i) Sum of Given first n terms of the AP
(ii)Sum of n terms of the AP
Question Number 23 of Exercise 11 C of RS Aggarwal Solution

Share

1 Answer

  1. The a_n term of the AP is given
    =(4n+1)
    so that a_1 is :
    a_1=4(1)+1
    a_1=5
    The Sum of first 15 terms of the AP is :
    S_15=n/2[a_1+a_15]
    S_15=15/2[5+4(15)+1]
    S_15=15/2[5+61]
    S_15=15/2×66
    S_15=495
    the sum of first 15 term is 495

    The sum of n Terms of the AP is:
    S_n=n/2[a_1+a_n]
    S_n=n/2[5+4n+1]
    S_n=n/2[6+4n]
    S_n=n[3+2n]
    the sum of n terms of the AP is n[3+2n]

    • -7
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