Advertisements
Advertisements
प्रश्न
Find the 20th term from the last term of the A.P. 3, 8, 13, …, 253.
Advertisements
उत्तर
Given A.P. is
3, 8, 13, …, 253
Common difference for this A.P. is 5.
Therefore, this A.P. can be written in reverse order as
253, 248, 243, …, 13, 8, 3
For this A.P.,
a = 253
d = 248 − 253
d = −5
n = 20
a20 = a + (20 − 1) d
a20 = 253 + (19) (−5)
a20 = 253 − 95
a = 158
Therefore, 20th term from the last term is 158.
संबंधित प्रश्न
If Sn denotes the sum of first n terms of an A.P., prove that S30 = 3[S20 − S10]
The first term of an A.P. is 5, the last term is 45 and the sum is 400. Find the number of terms and the common difference.
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.
Which term of the A.P. 121, 117, 113 … is its first negative term?
[Hint: Find n for an < 0]
Find how many integers between 200 and 500 are divisible by 8.
How many numbers are there between 101 and 999, which are divisible by both 2 and 5?
Divide 24 in three parts such that they are in AP and their product is 440.
If 18, a, (b - 3) are in AP, then find the value of (2a – b)
Which term of the AP 21, 18, 15, … is zero?
If `4/5 `, a, 2 are in AP, find the value of a.
The fourth term of an A.P. is 11. The sum of the fifth and seventh terms of the A.P. is 34. Find its common difference.
If the sum of first p terms of an A.P. is equal to the sum of first q terms then show that the sum of its first (p + q) terms is zero. (p ≠ q)
The 9th term of an A.P. is equal to 6 times its second term. If its 5th term is 22, find the A.P.
A man is employed to count Rs 10710. He counts at the rate of Rs 180 per minute for half an hour. After this he counts at the rate of Rs 3 less every minute than the preceding minute. Find the time taken by him to count the entire amount.
Write the common difference of an A.P. whose nth term is an = 3n + 7.
If \[\frac{1}{x + 2}, \frac{1}{x + 3}, \frac{1}{x + 5}\] are in A.P. Then, x =
If the sums of n terms of two arithmetic progressions are in the ratio \[\frac{3n + 5}{5n - 7}\] , then their nth terms are in the ratio
A manufacturer of TV sets produces 600 units in the third year and 700 units in the 7th year. Assuming that the production increases uniformly by a fixed number every year, find:
- the production in the first year.
- the production in the 10th year.
- the total production in 7 years.
Q.5
Q.13
Q.16
Q.18
The 11th term and the 21st term of an A.P are 16 and 29 respectively, then find the first term, common difference and the 34th term.
Find the value of x, when in the A.P. given below 2 + 6 + 10 + ... + x = 1800.
Find the common difference of an A.P. whose first term is 5 and the sum of first four terms is half the sum of next four terms.
The sum of the first 2n terms of the AP: 2, 5, 8, …. is equal to sum of the first n terms of the AP: 57, 59, 61, … then n is equal to ______.
Find the sum:
1 + (–2) + (–5) + (–8) + ... + (–236)
Find the sum of those integers from 1 to 500 which are multiples of 2 as well as of 5.
The students of a school decided to beautify the school on the Annual Day by fixing colourful flags on the straight passage of the school. They have 27 flags to be fixed at intervals of every 2 m. The flags are stored at the position of the middle most flag. Ruchi was given the responsibility of placing the flags. Ruchi kept her books where the flags were stored. She could carry only one flag at a time. How much distance did she cover in completing this job and returning back to collect her books? What is the maximum distance she travelled carrying a flag?
Find the sum of first 16 terms of the A.P. whose nth term is given by an = 5n – 3.
