Advertisements
Advertisements
प्रश्न
The 7th term of the an AP is -4 and its 13th term is -16. Find the AP.
Advertisements
उत्तर
We have
T7 = a + (n-1) d
⇒ a +6d = -4 ...............(1)
T13 = a +(n-1) d
⇒ a + 12d = -16 .................(2)
On solving (1) and (2), we get
a = 8 and d = - 2
Thus, first term = 8 and common difference = - 2
∴ The term of the AP are 8,6,4,2,.........
APPEARS IN
संबंधित प्रश्न
How many terms of the A.P. 27, 24, 21, .... should be taken so that their sum is zero?
In an AP given an = 4, d = 2, Sn = −14, find n and a.
Show that a1, a2,..., an... form an AP where an is defined as below:
an = 9 − 5n
Also, find the sum of the first 15 terms.
In a school, students thought of planting 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 the same as the class, in which they are studying, e.g., a section of class I will plant 1 tree, a section of class II will plant 2 trees, and so on till class XII. There are three sections of each class. How many trees will be planted by the students?
Find the sum of the following arithmetic progressions:
41, 36, 31, ... to 12 terms
Find the sum of the following arithmetic progressions
`(x - y)^2,(x^2 + y^2), (x + y)^2,.... to n term`
Find the sum of all 3 - digit natural numbers which are divisible by 13.
Find the sum of first 20 terms of the sequence whose nth term is `a_n = An + B`
The 24th term of an AP is twice its 10th term. Show that its 72nd term is 4 times its 15th term.
How many numbers are there between 101 and 999, which are divisible by both 2 and 5?
If the ratio of sum of the first m and n terms of an AP is m2 : n2, show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1) ?
The next term of the A.P. \[\sqrt{7}, \sqrt{28}, \sqrt{63}\] is ______.
Write the sum of first n even natural numbers.
In a Arithmetic Progression (A.P.) the fourth and sixth terms are 8 and 14 respectively. Find that:
(i) first term
(ii) common difference
(iii) sum of the first 20 terms.
Find the sum of first 10 terms of the A.P.
4 + 6 + 8 + .............
The sum of the first 15 multiples of 8 is ______.
The sum of first n terms of the series a, 3a, 5a, …….. is ______.
Find the sum of last ten terms of the AP: 8, 10, 12,.., 126.
Find the sum of first 'n' even natural numbers.
