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.
APPEARS IN
संबंधित प्रश्न
Find the 12th term from the end of the following arithmetic progressions:
3, 5, 7, 9, ... 201
The sum of three terms of an A.P. is 21 and the product of the first and the third terms exceed the second term by 6, find three terms.
Find the sum of all natural numbers between 1 and 100, which are divisible by 3.
Find the sum 3 + 11 + 19 + ... + 803
Find the sum of 28 terms of an A.P. whose nth term is 8n – 5.
Find the sum of first 51 terms of an A.P. whose 2nd and 3rd terms are 14 and 18 respectively.
The first term of an A.P. is 5, the last term is 45 and the sum of its terms is 1000. Find the number of terms and the common difference of the A.P.
Find the sum of all multiples of 7 lying between 300 and 700.
Which term of the A.P. `20, 19 1/4, 18 1/2, 17 3/4,` ..... is the first negative term?
The 4th term of an AP is zero. Prove that its 25th term is triple its 11th term.
If the numbers a, 9, b, 25 from an AP, find a and b.
What is the sum of first n terms of the AP a, 3a, 5a, …..
In an A.P. sum of three consecutive terms is 27 and their product is 504, find the terms.
(Assume that three consecutive terms in A.P. are a – d, a, a + d).
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.
The 19th term of an A.P. is equal to three times its sixth term. If its 9th term is 19, find the 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?
For what value of p are 2p + 1, 13, 5p − 3 are three consecutive terms of an A.P.?
Q.6
Obtain the sum of the first 56 terms of an A.P. whose 18th and 39th terms are 52 and 148 respectively.
If the third term of an A.P. is 1 and 6th term is – 11, find the sum of its first 32 terms.
In an A.P., the sum of its first n terms is 6n – n². Find is 25th term.
Find the sum of first 1000 positive integers.
Activity :- Let 1 + 2 + 3 + ........ + 1000
Using formula for the sum of first n terms of an A.P.,
Sn = `square`
S1000 = `square/2 (1 + 1000)`
= 500 × 1001
= `square`
Therefore, Sum of the first 1000 positive integer is `square`
The sum of first n terms of the series a, 3a, 5a, …….. is ______.
Find the sum of those integers from 1 to 500 which are multiples of 2 or 5.
[Hint (iii) : These numbers will be : multiples of 2 + multiples of 5 – multiples of 2 as well as of 5]
If the first term of an AP is –5 and the common difference is 2, then the sum of the first 6 terms is ______.
Find the sum:
1 + (–2) + (–5) + (–8) + ... + (–236)
If sum of first 6 terms of an AP is 36 and that of the first 16 terms is 256, find the sum of first 10 terms.
If 7 times the seventh term of the AP is equal to 5 times the fifth term, then find the value of its 12th term.
If the last term of an A.P. of 30 terms is 119 and the 8th term from the end (towards the first term) is 91, then find the common difference of the A.P. Hence, find the sum of all the terms of the A.P.
Solve the equation:
– 4 + (–1) + 2 + 5 + ... + x = 437
