Advertisements
Advertisements
प्रश्न
If the first term of an AP is –5 and the common difference is 2, then the sum of the first 6 terms is ______.
विकल्प
0
5
6
15
Advertisements
उत्तर
If the first term of an AP is –5 and the common difference is 2, then the sum of the first 6 terms is 0.
Explanation:
Given,
a = –5
And d = 2
∴ S6 = `6/2[2a + (6 - 1)d]` ...`[∵ S_n = n/2[2a + (n - 1)d]]`
= 3[2(–5) + 5(2)]
= 3(–10 + 10)
= 0
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.
The houses in a row numbered consecutively from 1 to 49. Show that there exists a value of x such that sum of numbers of houses preceding the house numbered x is equal to sum of the numbers of houses following x.
If the sum of the first n terms of an A.P. is `1/2`(3n2 +7n), then find its nth term. Hence write its 20th term.
How many terms are there in the A.P. whose first and fifth terms are −14 and 2 respectively and the sum of the terms is 40?
Find the sum of all integers between 100 and 550, which are divisible by 9.
Find the sum 2 + 4 + 6 ... + 200
Find the sum of the first 15 terms of each of the following sequences having the nth term as
`a_n = 3 + 4n`
In an A.P. the first term is 25, nth term is –17 and the sum of n terms is 132. Find n and the common difference.
If the numbers (2n – 1), (3n+2) and (6n -1) are in AP, find the value of n and the numbers
The first term of an AP is p and its common difference is q. Find its 10th term.
Choose the correct alternative answer for the following question .
In an A.P. 1st term is 1 and the last term is 20. The sum of all terms is = 399 then n = ....
If the sum of first p terms of an A.P. is equal to the sum of first q terms then show that the sum of its first (p + q) terms is zero. (p ≠ q)
Find out the sum of all natural numbers between 1 and 145 which are divisible by 4.
Q.1
If the sum of the first four terms of an AP is 40 and that of the first 14 terms is 280. Find the sum of its first n terms.
The sum of the first three numbers in an Arithmetic Progression is 18. If the product of the first and the third term is 5 times the common difference, find the three numbers.
Find the sum of first seven numbers which are multiples of 2 as well as of 9.
If the first term of an A.P. is 5, the last term is 15 and the sum of first n terms is 30, then find the value of n.
The nth term of an Arithmetic Progression (A.P.) is given by the relation Tn = 6(7 – n)..
Find:
- its first term and common difference
- sum of its first 25 terms
