Advertisements
Advertisements
प्रश्न
The first and last terms of an AP are 17 and 350, respectively. If the common difference is 9, how many terms are there, and what is their sum?
Advertisements
उत्तर
Given that,
a = 17
l = 350
d = 9
Let there be n terms in the A.P.
l = a + (n – 1)d
350 = 17 + (n – 1)9
9n = 350 + 9 – 17
9n = 359 – 17
9n = 342
⇒ n = `342/9`
⇒ n = 38
Sn = `n/2 (a + l)`
Sn = `38/2 (17 + 350)`
= 19 × 367
= 6973
Thus, this A.P. contains 38 terms and the sum of the terms of this A.P. is 6973.
APPEARS IN
संबंधित प्रश्न
In an A.P., if S5 + S7 = 167 and S10=235, then find the A.P., where Sn denotes the sum of its first n terms.
Check whether -150 is a term of the A.P. 11, 8, 5, 2, ....
How many terms of the A.P. : 24, 21, 18, ................ must be taken so that their sum is 78?
If 4 times the 4th term of an A.P. is equal to 18 times its 18th term, then find its 22nd term.
If the sum of three consecutive terms of an increasing A.P. is 51 and the product of the first and third of these terms is 273, then the third term is
If Sr denotes the sum of the first r terms of an A.P. Then , S3n: (S2n − Sn) is
Q.6
If a = 6 and d = 10, then find S10.
Find the next 4 terms of the sequence `1/6, 1/4, 1/3`. Also find Sn.
Find the sum of the integers between 100 and 200 that are not divisible by 9.
