Advertisements
Advertisements
प्रश्न
In an A.P. a = 2 and d = 3, then find S12
Advertisements
उत्तर
a = 2 and d = 3 ......[Given]
Since Sn = `"n"/2 [2"a" + ("n" - 1)"d"]`,
S12 = `12/2 [2(2) + (12 - 1)(3)]`
= 6[4 + 11(3)]
= 6(4 + 33)
= 6(37)
= 222
APPEARS IN
संबंधित प्रश्न
How many terms of the A.P. 27, 24, 21, .... should be taken so that their sum is zero?
Find the sum of first 40 positive integers divisible by 6.
If the pth term of an A. P. is `1/q` and qth term is `1/p`, prove that the sum of first pq terms of the A. P. is `((pq+1)/2)`.
Find the sum of the following arithmetic progressions:
1, 3, 5, 7, ... to 12 terms
Find the sum of the following arithmetic progressions:
41, 36, 31, ... to 12 terms
Find the sum of the following arithmetic progressions:
a + b, a − b, a − 3b, ... to 22 terms
The first and the last terms of an A.P. are 34 and 700 respectively. If the common difference is 18, how many terms are there and what is their sum?
Find the sum of first n even natural numbers.
For what value of p are 2p + 1, 13, 5p − 3 are three consecutive terms of an A.P.?
If the sum of n terms of an A.P. be 3n2 + n and its common difference is 6, then its first term is ______.
Two A.P.'s have the same common difference. The first term of one of these is 8 and that of the other is 3. The difference between their 30th term is
If 18, a, b, −3 are in A.P., the a + b =
Which term of the AP 3, 15, 27, 39, ...... will be 120 more than its 21st term?
Find the sum of all members from 50 to 250 which divisible by 6 and find t13.
Find the value of x, when in the A.P. given below 2 + 6 + 10 + ... + x = 1800.
In an A.P. (with usual notations) : given d = 5, S9 = 75, find a and a9
Shubhankar invested in a national savings certificate scheme. In the first year he invested ₹ 500, in the second year ₹ 700, in the third year ₹ 900 and so on. Find the total amount that he invested in 12 years
If the sum of first n terms of an AP is An + Bn² where A and B are constants. The common difference of AP will be ______.
Measures of angles of a triangle are in A.P. The measure of smallest angle is five times of common difference. Find the measures of all angles of a triangle. (Assume the measures of angles as a, a + d, a + 2d)
Find the sum of first 20 terms of an A.P. whose nth term is given as an = 5 – 2n.
