Advertisements
Advertisements
प्रश्न
The sum of first 16 terms of the AP: 10, 6, 2,... is ______.
पर्याय
–320
320
–352
–400
Advertisements
उत्तर
The sum of first 16 terms of the AP: 10, 6, 2,... is –320.
Explanation:
Given, AP is 10, 6, 2,...
Here,
First term a = 10,
Common difference,
d = – 4
∴ S16 = `16/2[2a + (16 - 1)d]` ...`[∵ S_n = n/2[2a + (n - 1)d]]`
= 8[2 × 10 + 15(– 4)]
= 8(20 – 60)
= 8(– 40)
= – 320
APPEARS IN
संबंधित प्रश्न
Find four numbers in A.P. whose sum is 20 and the sum of whose squares is 120
Check whether -150 is a term of the A.P. 11, 8, 5, 2, ....
Show that a1, a2,..., an... form an AP where an is defined as below:
an = 3 + 4n
Also, find the sum of the first 15 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.
Find how many integers between 200 and 500 are divisible by 8.
Find the sum of the first 25 terms of an A.P. whose nth term is given by an = 7 − 3n
Find the sum of first n odd natural numbers
If `4/5 `, a, 2 are in AP, find the value of a.
Find the first term and common difference for the A.P.
127, 135, 143, 151,...
The first term of an A. P. is 5 and the common difference is 4. Complete the following activity and find the sum of the first 12 terms of the A. P.
a = 5, d = 4, s12 = ?
`s_n = n/2 [ square ]`
`s_12 = 12/2 [10 +square]`
`= 6 × square `
` =square`
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 the sum of first n even natural numbers is equal to k times the sum of first n odd natural numbers, then k =
Q.13
Q.14
Q.19
Q.20
Find second and third terms of an A.P. whose first term is – 2 and the common difference is – 2.
The sum of first ten natural number is ______.
Find the sum of first seven numbers which are multiples of 2 as well as of 9.
