Advertisements
Advertisements
प्रश्न
The Sum of first five multiples of 3 is ______.
विकल्प
45
55
15
75
उत्तर
The Sum of first five multiples of 3 is 45.
Explanation:-
The given sequence is 3, 6, 9,...
Here,
a = 3
d = 3
n = 5
Therefore,
`S_n = n/2(2a+(n-1)d)`
`S_5 = 5/2(2a+(5-1)d)`
`=5/2(2(3)+4(3))`
`=5/2(6+12)`
`=5/2(18)`
`=5(9)`
= 45
संबंधित प्रश्न
How many terms of the A.P. 18, 16, 14, .... be taken so that their sum is zero?
If the sum of first 7 terms of an A.P. is 49 and that of its first 17 terms is 289, find the sum of first n terms of the A.P.
Find the 20th term from the last term of the A.P. 3, 8, 13, …, 253.
Find the sum of the following APs.
−37, −33, −29, …, to 12 terms.
How many terms of the AP. 9, 17, 25 … must be taken to give a sum of 636?
Three numbers are in A.P. If the sum of these numbers is 27 and the product 648, find the numbers.
Find the sum of the following arithmetic progressions:
`(x - y)/(x + y),(3x - 2y)/(x + y), (5x - 3y)/(x + y)`, .....to n terms
Find the sum of all natural numbers between 250 and 1000 which are divisible by 9.
Is 184 a term of the AP 3, 7, 11, 15, ….?
What is the sum of first n terms of the AP a, 3a, 5a, …..
Find the sum of first n even natural numbers.
Find the sum of the following Aps:
9, 7, 5, 3 … to 14 terms
Find the sum of all multiples of 9 lying between 300 and 700.
For what value of n, the nth terms of the arithmetic progressions 63, 65, 67, ... and 3, 10, 17, ... equal?
If the seventh term of an A.P. is \[\frac{1}{9}\] and its ninth term is \[\frac{1}{7}\] , find its (63)rd term.
The sum of the first n terms of an A.P. is 3n2 + 6n. Find the nth term of this A.P.
A piece of equipment cost a certain factory Rs 60,000. If it depreciates in value, 15% the first, 13.5% the next year, 12% the third year, and so on. What will be its value at the end of 10 years, all percentages applying to the original cost?
Write the nth term of an A.P. the sum of whose n terms is Sn.
If the sum of first n even natural numbers is equal to k times the sum of first n odd natural numbers, then k =
Let the four terms of the AP be a − 3d, a − d, a + d and a + 3d. find A.P.
Q.6
Find the sum of first 10 terms of the A.P.
4 + 6 + 8 + .............
Find the sum of first 20 terms of an A.P. whose first term is 3 and the last term is 57.
Find the sum of natural numbers between 1 to 140, which are divisible by 4.
Activity: Natural numbers between 1 to 140 divisible by 4 are, 4, 8, 12, 16,......, 136
Here d = 4, therefore this sequence is an A.P.
a = 4, d = 4, tn = 136, Sn = ?
tn = a + (n – 1)d
`square` = 4 + (n – 1) × 4
`square` = (n – 1) × 4
n = `square`
Now,
Sn = `"n"/2["a" + "t"_"n"]`
Sn = 17 × `square`
Sn = `square`
Therefore, the sum of natural numbers between 1 to 140, which are divisible by 4 is `square`.
The sum of first 16 terms of the AP: 10, 6, 2,... is ______.
The sum of the first five terms of an AP and the sum of the first seven terms of the same AP is 167. If the sum of the first ten terms of this AP is 235, find the sum of its first twenty terms.
In an AP, if Sn = n(4n + 1), find the AP.
Kanika was given her pocket money on Jan 1st, 2008. She puts Rs 1 on Day 1, Rs 2 on Day 2, Rs 3 on Day 3, and continued doing so till the end of the month, from this money into her piggy bank. She also spent Rs 204 of her pocket money, and found that at the end of the month she still had Rs 100 with her. How much was her pocket money for the month?
Yasmeen saves Rs 32 during the first month, Rs 36 in the second month and Rs 40 in the third month. If she continues to save in this manner, in how many months will she save Rs 2000?
The sum of 40 terms of the A.P. 7 + 10 + 13 + 16 + .......... is ______.
