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
In an AP given d = 5, S9 = 75, find a and a9.
If (m + 1)th term of an A.P is twice the (n + 1)th term, prove that (3m + 1)th term is twice the (m + n + 1)th term.
If (2p + 1), 13, (5p - 3) are in AP, find the value of p.
If the ratio of sum of the first m and n terms of an AP is m2 : n2, show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1) ?
If the 10th term of an A.P. is 21 and the sum of its first 10 terms is 120, find its nth term.
If \[\frac{5 + 9 + 13 + . . . \text{ to n terms} }{7 + 9 + 11 + . . . \text{ to (n + 1) terms}} = \frac{17}{16},\] then n =
How many terms of the A.P. 27, 24, 21, …, should be taken so that their sum is zero?
First four terms of the sequence an = 2n + 3 are ______.
Solve the equation
– 4 + (–1) + 2 + ... + x = 437
The sum of the 4th and 8th term of an A.P. is 24 and the sum of the 6th and 10th term of the A.P. is 44. Find the A.P. Also, find the sum of first 25 terms of the A.P.
