Advertisements
Advertisements
प्रश्न
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.
Advertisements
उत्तर
t11 = 16 and t21 = 29
t1 = ?, d = ? and t34 = ?
tn = a + (n - 1) d
t11 = a + (11 - 1) d
16 = a + 10 d ......(1)
t21 = a + (21 - 1) d
29 = a + 20d .........(2)
Subtracting equation (1) and (2)
a + 20 d = 29
a + 10 d = 16
_________________
10 d = 13
d = `13/10`
d = 1.3
Substituting d = 1.3 in equation (1)
16 = a + 10 d
a + 10 (1.3) = 16
a + 13 = 16
a = 16 - 13
a = 3
t34 = 3 + (34 - 1) (1.3)
= 3 + 33(1.3)
= 3 + 42.9
t34 = 45.9
APPEARS IN
संबंधित प्रश्न
In an AP given d = 5, S9 = 75, find a and a9.
A ladder has rungs 25 cm apart. (See figure). The rungs decrease uniformly in length from 45 cm at the bottom to 25 cm at the top. If the top and bottom rungs are 2 `1/2` m apart, what is the length of the wood required for the rungs?
[Hint: number of rungs = `250/25+ 1`]
In an A.P., if the first term is 22, the common difference is −4 and the sum to n terms is 64, find n.
Write an A.P. whose first term is a and common difference is d in the following.
a = –3, d = 0
Choose the correct alternative answer for the following question .
15, 10, 5,... In this A.P sum of first 10 terms is...
Find the A.P. whose fourth term is 9 and the sum of its sixth term and thirteenth term is 40.
Fill up the boxes and find out the number of terms in the A.P.
1,3,5,....,149 .
Here a = 1 , d =b`[ ], t_n = 149`
tn = a + (n-1) d
∴ 149 =`[ ] ∴149 = 2n - [ ]`
∴ n =`[ ]`
If 18, a, b, −3 are in A.P., the a + b =
Which term of the AP 3, 15, 27, 39, ...... will be 120 more than its 21st term?
If the second term and the fourth term of an A.P. are 12 and 20 respectively, then find the sum of first 25 terms:
Find the sum of all members from 50 to 250 which divisible by 6 and find t13.
Show that a1, a2, a3, … form an A.P. where an is defined as an = 3 + 4n. Also find the sum of first 15 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`
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?
The sum of first ten natural number is ______.
In an AP if a = 1, an = 20 and Sn = 399, then n is ______.
In an A.P., if Sn = n(4n + 1), find the A.P.
Find the sum of first seven numbers which are multiples of 2 as well as of 9.
Three numbers in A.P. have the sum of 30. What is its middle term?
