Advertisements
Advertisements
प्रश्न
Write the nth term of an A.P. the sum of whose n terms is Sn.
Advertisements
उत्तर
We are given an A.P. the sum of whose n terms is Sn. So, to calculate the nth term of the A.P. we use following formula,
an = Sn - Sn-1
So, the nth term of the A.P. is given by an = Sn - Sn-1 .
APPEARS IN
संबंधित प्रश्न
In an A.P., if S5 + S7 = 167 and S10=235, then find the A.P., where Sn denotes the sum of its first n terms.
Find the sum of first 30 terms of an A.P. whose second term is 2 and seventh term is 22
The sum of n, 2n, 3n terms of an A.P. are S1 , S2 , S3 respectively. Prove that S3 = 3(S2 – S1 )
Find the sum of the following APs.
−37, −33, −29, …, to 12 terms.
Show that a1, a2,..., an... form an AP where an is defined as below:
an = 9 − 5n
Also, find the sum of the first 15 terms.
If the sum of the first n terms of an AP is 4n − n2, what is the first term (that is, S1)? What is the sum of the first two terms? What is the second term? Similarly, find the 3rd, the 10th, and the nth terms.
Find the sum of n terms of an A.P. whose nth terms is given by an = 5 − 6n.
Determine k so that (3k -2), (4k – 6) and (k +2) are three consecutive terms of an AP.
Which term of the AP 21, 18, 15, … is zero?
The first term of an AP is p and its common difference is q. Find its 10th term.
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) ?
What is the sum of first 10 terms of the A. P. 15,10,5,........?
The sum of 5th and 9th terms of an A.P. is 30. If its 25th term is three times its 8th term, find the A.P.
The sum of the first n terms of an A.P. is 3n2 + 6n. Find the nth term of this A.P.
If the sum of n terms of an A.P. is 2n2 + 5n, then its nth term is
The first three terms of an A.P. respectively are 3y − 1, 3y + 5 and 5y + 1. Then, y equals
A manufacturer of TV sets produces 600 units in the third year and 700 units in the 7th year. Assuming that the production increases uniformly by a fixed number every year, find:
- the production in the first year.
- the production in the 10th year.
- the total production in 7 years.
Q.14
The ratio of the 11th term to the 18th term of an AP is 2 : 3. Find the ratio of the 5th term to the 21st term, and also the ratio of the sum of the first five terms to the sum of the first 21 terms.
Solve the equation:
– 4 + (–1) + 2 + 5 + ... + x = 437
