Advertisements
Advertisements
प्रश्न
Find the sum of 28 terms of an A.P. whose nth term is 8n – 5.
Advertisements
उत्तर
nth term of an A.P. = tn = 8n – 5
Let a be the first term and d be the common difference of this A.P.
Then,
a = t1
= 8 × 1 – 5
= 8 – 5
= 3
t2 = 8 × 2 – 5
= 16 – 5
= 11
∴ d = t2 – t1
= 11 – 3
= 8
The sum of n terms of an A.P. = `S = n/2 [2a + (n - 1)d]`
`=>` Sum of 28 terms of an A.P. = `28/2 [2 xx 3 + 27 xx 8]`
= 14[6 + 216]
= 14 × 222
= 3108
APPEARS IN
संबंधित प्रश्न
The sum of three numbers in A.P. is –3, and their product is 8. Find the numbers
Find the sum of all integers between 84 and 719, which are multiples of 5.
Find the sum of the first 51 terms of the A.P: whose second term is 2 and the fourth term is 8.
In an A.P. the first term is 25, nth term is –17 and the sum of n terms is 132. Find n and the common difference.
Is 184 a term of the AP 3, 7, 11, 15, ….?
Find the sum of the first 15 terms of each of the following sequences having nth term as xn = 6 − n .
Q.12
The famous mathematician associated with finding the sum of the first 100 natural numbers is ______.
In the month of April to June 2022, the exports of passenger cars from India increased by 26% in the corresponding quarter of 2021-22, as per a report. A car manufacturing company planned to produce 1800 cars in 4th year and 2600 cars in 8th year. Assuming that the production increases uniformly by a fixed number every year. |
Based on the above information answer the following questions.
- Find the production in the 1st year
- Find the production in the 12th year.
- Find the total production in first 10 years.
[OR]
In how many years will the total production reach 31200 cars?
