Advertisements
Advertisements
प्रश्न
The first term of an A. P. is 5 and the common difference is 4. Complete the following activity and find the sum of the first 12 terms of the A. P.
a = 5, d = 4, s12 = ?
`s_n = n/2 [ square ]`
`s_12 = 12/2 [10 +square]`
`= 6 × square `
` =square`
Advertisements
उत्तर
`s_n = n/2 [ 2a +(n-1)d ]`
`s_12 = 12/2 [10 + 11 xx 4 ]`
` =12/2[10+44]`
`= 6 ×54 `
` s_n= 324`
संबंधित प्रश्न
If the sum of first 7 terms of an A.P. is 49 and that of its first 17 terms is 289, find the sum of first n terms of the A.P.
The ratio of the sum use of n terms of two A.P.’s is (7n + 1) : (4n + 27). Find the ratio of their mth terms
Find the sum of the first 40 positive integers divisible by 5.
Find the sum of all 3-digit natural numbers, which are multiples of 11.
If the 10th term of an AP is 52 and 17th term is 20 more than its 13th term, find the AP.
The 4th term of an AP is 11. The sum of the 5th and 7th terms of this AP is 34. Find its common difference.
Find four numbers in AP whose sum is 28 and the sum of whose squares is 216.
Sum of 1 to n natural numbers is 36, then find the value of n.
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 ?
The sum of 5th and 9th terms of an A.P. is 30. If its 25th term is three times its 8th term, find the A.P.
Let there be an A.P. with first term 'a', common difference 'd'. If an denotes in nth term and Sn the sum of first n terms, find.
If the sum of first n even natural numbers is equal to k times the sum of first n odd natural numbers, then k =
The sum of n terms of two A.P.'s are in the ratio 5n + 9 : 9n + 6. Then, the ratio of their 18th term is
The common difference of the A.P. is \[\frac{1}{2q}, \frac{1 - 2q}{2q}, \frac{1 - 4q}{2q}, . . .\] is
Q.5
Find second and third terms of an A.P. whose first term is – 2 and the common difference is – 2.
Find the sum of odd natural numbers from 1 to 101.
Find the sum of 12 terms of an A.P. whose nth term is given by an = 3n + 4.
Find the sum of first 16 terms of the A.P. whose nth term is given by an = 5n – 3.
Find the sum of the first 100 terms of the A.P. \[14, 16, 18, \ldots\]
