Advertisements
Advertisements
प्रश्न
Which term of the Arithmetic Progression (A.P.) 15, 30, 45, 60...... is 300?
Hence find the sum of all the terms of the Arithmetic Progression (A.P.)
Advertisements
उत्तर
Given A.P. is 15, 30, 45, 60.........
Here a = 15, d = 30 – 15 = 15
Let Tn = 300
Tn = a + (n – 1)d
300 = 15 + (n – 1) × 15
300 = 15 + 15n – 15
15n = 300
∴ n = 20
Hence, 300 is the 20th term
Also by Sn = `n/2 [2a + (n - 1)d]`
S20 = `20/2 [2 xx 15 + (20 - 1) xx 15]`
= 10[30 + 285]
= 10 × 315
∴ S20 = 3150
APPEARS IN
संबंधित प्रश्न
If the 3rd and the 9th terms of an AP are 4 and –8 respectively, which term of this AP is zero?
If the numbers a, 9, b, 25 from an AP, find a and b.
Find the 25th term of the AP \[- 5, \frac{- 5}{2}, 0, \frac{5}{2}, . . .\]
If the common differences of an A.P. is 3, then a20 − a15 is
In an A.P., the first term is 22, nth term is −11 and the sum to first n terms is 66. Find n and d, the common difference
Obtain the sum of the first 56 terms of an A.P. whose 18th and 39th terms are 52 and 148 respectively.
The famous mathematician associated with finding the sum of the first 100 natural numbers is ______.
The first term of an AP of consecutive integers is p2 + 1. The sum of 2p + 1 terms of this AP is ______.
Find the sum:
`4 - 1/n + 4 - 2/n + 4 - 3/n + ...` upto n terms
The sum of n terms of an A.P. is 3n2. The second term of this A.P. is ______.
