Advertisements
Advertisements
Question
Find the sum of the first 22 terms of the A.P. : 8, 3, –2, ………
Advertisements
Solution
The given A.P. is 8, 3, –2, ………
Here, a = 8, d = 3 – 8 = –5 and n = 22
∴ `S = n/2[2a + (n - 1)d]`
= `22/2 [2 xx 8 + (22 - 1) xx (-5)]`
= 11[16 + 21 × (–5)]
= 11[16 – 105]
= 11 × (–89)
= –979
APPEARS IN
RELATED QUESTIONS
If the ratio of the sum of the first n terms of two A.Ps is (7n + 1) : (4n + 27), then find the ratio of their 9th terms.
The 7th term of the an AP is -4 and its 13th term is -16. Find the AP.
The 4th term of an AP is 11. The sum of the 5th and 7th terms of this AP is 34. Find its common difference
What is the 5th term form the end of the AP 2, 7, 12, …., 47?
The sum of the first n terms of an AP in `((5n^2)/2 + (3n)/2)`.Find its nth term and the 20th term of this AP.
Q.6
The middle most term(s) of the AP: -11, -7, -3,.... 49 is ______.
If Sn denotes the sum of first n terms of an AP, prove that S12 = 3(S8 – S4)
Find the sum of last ten terms of the AP: 8, 10, 12,.., 126.
In a ‘Mahila Bachat Gat’, Kavita invested from the first day of month ₹ 20 on first day, ₹ 40 on second day and ₹ 60 on third day. If she saves like this, then what would be her total savings in the month of February 2020?
