Advertisements
Advertisements
प्रश्न
If the common differences of an A.P. is 3, then a20 − a15 is
पर्याय
A. 5
B. 3
C. 15
D. 20
Advertisements
उत्तर
Let the first term of the A.P. be a.
`a_n=a(n-1)d`
`a_20-a_15=[a+(20-1)d]-[a+(15-1)d]`
`=19d-14b`
`=5d`
`=5xx3`
`=15`
The correct answer is C.
APPEARS IN
संबंधित प्रश्न
How many terms of the series 54, 51, 48, …. be taken so that their sum is 513 ? Explain the double answer
If (m + 1)th term of an A.P is twice the (n + 1)th term, prove that (3m + 1)th term is twice the (m + n + 1)th term.
Find the sum of all natural numbers between 250 and 1000 which are divisible by 9.
If the numbers (2n – 1), (3n+2) and (6n -1) are in AP, find the value of n and the numbers
If (2p +1), 13, (5p -3) are in AP, find the value of p.
Find the first term and common difference for the following A.P.:
5, 1, –3, –7, ...
There are 25 rows of seats in an auditorium. The first row is of 20 seats, the second of 22 seats, the third of 24 seats, and so on. How many chairs are there in the 21st row ?
x is nth term of the given A.P. an = x find x .
The middle most term(s) of the AP: -11, -7, -3,.... 49 is ______.
The first term of an AP of consecutive integers is p2 + 1. The sum of 2p + 1 terms of this AP is ______.
