Advertisements
Advertisements
प्रश्न
For an A.P., if t1 = 1 and tn = 149, then find Sn.
Activitry :- Here t1= 1, tn = 149, Sn = ?
Sn = `n/2 (square + square)`
= `n/2 xx square`
= `square` n, where n = 75
Advertisements
उत्तर
Here, t1= 1, tn = 149, Sn = ?
Sn = \[\frac{n}{2} (\boxed{t_1} + \boxed{t_n})\]
= `n/2 (1 + 149)`
= \[\frac{n}{2} \times \boxed{150}\]
= \[\boxed{75}\] n, where n = 75
APPEARS IN
संबंधित प्रश्न
Show that the sum of all odd integers between 1 and 1000 which are divisible by 3 is 83667.
How many terms of the A.P. : 24, 21, 18, ................ must be taken so that their sum is 78?
Find the sum of all multiples of 7 lying between 300 and 700.
Which term of the AP `5/6, 1, 1 1/6, 1 1/3,` ... is 3?
The 7th term of an AP is –4 and its 13th term is –16. Find the AP.
The 19th term of an AP is equal to 3 times its 6th term. If its 9th term is 19, find the AP.
If (3y – 1), (3y + 5) and (5y + 1) are three consecutive terms of an AP then find the value of y.
Find the sum of the first n natural numbers.
Find the sum of all natural numbers between 200 and 400 which are divisible by 7.
Find the first term and common difference for the A.P.
0.6, 0.9, 1.2,1.5,...
Sum of 1 to n natural numbers is 36, then find the value of n.
There are 37 terms in an A.P., the sum of three terms placed exactly at the middle is 225 and the sum of last three terms is 429. Write the A.P.
Rs 1000 is invested at 10 percent simple interest. Check at the end of every year if the total interest amount is in A.P. If this is an A.P. then find interest amount after 20 years. For this complete the following activity.
The 19th term of an A.P. is equal to three times its sixth term. If its 9th term is 19, find the A.P.
If the sum of first n terms of an A.P. is \[\frac{1}{2}\] (3n2 + 7n), then find its nth term. Hence write its 20th term.
If the sum of n terms of an A.P. is 3n2 + 5n then which of its terms is 164?
If the sum of first n even natural numbers is equal to k times the sum of first n odd natural numbers, then k =
Find whether 55 is a term of the A.P. 7, 10, 13,... or not. If yes, find which term is it.
The middle most term(s) of the AP: -11, -7, -3,.... 49 is ______.
Rohan repays his total loan of ₹ 1,18,000 by paying every month starting with the first installment of ₹ 1,000. If he increases the installment by ₹ 100 every month, what amount will be paid by him in the 30th installment? What amount of loan has he paid after 30th installment?
