Advertisements
Advertisements
प्रश्न
Find the sum of the following APs.
−37, −33, −29, …, to 12 terms.
Advertisements
उत्तर
−37, −33, −29, …, to 12 terms
For this A.P.,
a = −37
d = a2 − a1
= (−33) − (−37)
= −33 + 37
= 4
n = 12
We know that,
Sn = `n/2 [2a+(n - 1) d]`
S12 = `12/2 [2(-37)+(12 - 1) × 4]`
= 6[-74 + 11 × 4]
= 6[-74 + 44]
= 6(-30)
= -180
Thus, the sum of first 12 terms is -180.
संबंधित प्रश्न
The first and the last terms of an AP are 7 and 49 respectively. If sum of all its terms is 420, find its common difference.
An A.P. consists of 50 terms of which 3rd term is 12 and the last term is 106. Find the 29th term of the A.P.
Find the sum of the following APs:
2, 7, 12, ..., to 10 terms.
The 9th term of an AP is -32 and the sum of its 11th and 13th terms is -94. Find the common difference of the AP.
Show that `(a-b)^2 , (a^2 + b^2 ) and ( a^2+ b^2) ` are in AP.
Find the first term and common difference for the A.P.
`1/4,3/4,5/4,7/4,...`
Kargil’s temperature was recorded in a week from Monday to Saturday. All readings were in A.P. The sum of temperatures of Monday and Saturday was 5°C more than sum of temperatures of Tuesday and Saturday. If temperature of Wednesday was –30° celsius then find the temperature on the other five days.
What is the sum of first 10 terms of the A. P. 15,10,5,........?
Find the sum: 1 + 3 + 5 + 7 + ... + 199 .
The sum of first n terms of an A.P. is 5n − n2. Find the nth term of this A.P.
In a school, students decided to plant trees in and around the school to reduce air pollution. It was decided that the number of trees, that each section of each class will plant, will be double of the class in which they are studying. If there are 1 to 12 classes in the school and each class has two sections, find how many trees were planted by the students.
If Sn denotes the sum of the first n terms of an A.P., prove that S30 = 3(S20 − S10)
If the first term of an A.P. is 2 and common difference is 4, then the sum of its 40 terms is
Q.10
Which term of the AP 3, 15, 27, 39, ...... will be 120 more than its 21st term?
Obtain the sum of the first 56 terms of an A.P. whose 18th and 39th terms are 52 and 148 respectively.
Find the sum of three-digit natural numbers, which are divisible by 4
What is the sum of an odd numbers between 1 to 50?
In a ‘Mahila Bachat Gat’, Sharvari invested ₹ 2 on first day, ₹ 4 on second day and ₹ 6 on third day. If she saves like this, then what would be her total savings in the month of February 2010?
If ₹ 3900 will have to be repaid in 12 monthly instalments such that each instalment being more than the preceding one by ₹ 10, then find the amount of the first and last instalment
