Advertisements
Advertisements
प्रश्न
Find the sum of first seven numbers which are multiples of 2 as well as of 9.
Advertisements
उत्तर
For finding the sum of first seven numbers which are multiples of 2 as well as of 9.
Take LCM of 2 and 9 which is 18.
So, the series becomes 18, 36, 54,...
Here, first term (a) = 18,
Common difference (d) = 36 – 18 = 18
∵ Sn = `n/2[2a + (n - 1)d]`
S7 = `7/2[2(18) + (7 - 1)8]`
= `7/2[36 + (6 xx 18)]`
= 7(18 + 3 × 18)
= 7(18 + 54)
= 7 × 72
= 504
APPEARS IN
संबंधित प्रश्न
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.
Find the sum of all natural numbers between 1 and 100, which are divisible by 3.
Find the sum of all odd numbers between 100 and 200.
In an A.P., the sum of first n terms is `(3n^2)/2 + 13/2 n`. Find its 25th term.
How many terms of the A.P. : 24, 21, 18, ................ must be taken so that their sum is 78?
Determine the nth term of the AP whose 7th term is -1 and 16th term is 17.
If the sum of first m terms of an AP is ( 2m2 + 3m) then what is its second term?
Find the sum of all multiples of 9 lying between 300 and 700.
Write an A.P. whose first term is a and common difference is d in the following.
a = –19, d = –4
If m times the mth term of an A.P. is eqaul to n times nth term then show that the (m + n)th term of the A.P. is zero.
For what value of n, the nth terms of the arithmetic progressions 63, 65, 67, ... and 3, 10, 17, ... equal?
The given terms are 2k + 1, 3k + 3 and 5k − 1. find AP.
In an AP if a = 1, an = 20 and Sn = 399, then n is ______.
Find the sum of 12 terms of an A.P. whose nth term is given by an = 3n + 4.
Find the sum of those integers from 1 to 500 which are multiples of 2 as well as of 5.
Find the sum of all odd numbers between 351 and 373.
Assertion (A): a, b, c are in A.P. if and only if 2b = a + c.
Reason (R): The sum of first n odd natural numbers is n2.
The sum of A.P. 4, 7, 10, 13, ........ upto 20 terms is ______.
The sum of 40 terms of the A.P. 7 + 10 + 13 + 16 + .......... is ______.
k + 2, 2k + 7 and 4k + 12 are the first three terms of an A.P. The first term of this A.P. is ______.
