CBSE Class 10 Answered
how many terms of an AP 1,4,7...must be taken to give a sum of 51?
Asked by jaiprakashprasadr | 17 Jul, 2022, 23:03: PM
Hint
To find 'n' = number of terms.
Given:
AP as 1, 4, 7, ...,
Sn = 51.
a = 1
d = 3 (4 - 1 = 3, 7 - 4 = 3).
Sn = (n/2)[2a + (n - 1)d]
51 = (n/2)[2 + 3n - 3]
102 = n(3n - 1)
so,
3n2 - n - 102 = 0
3n2 - 18n + 17n - 102 = 0
3n(n - 6) + 17(n - 6) = 0
(n - 6)(3n + 17) = 0
Solving this gives us n = 6 and a negative number.
A total of six terms must be taken from the AP to obtain 51.
A total of six terms must be taken from the AP to obtain 51.
Answered by | 18 Jul, 2022, 00:37: AM
Application Videos
Concept Videos
CBSE 10 - Maths
Asked by lp9128437598 | 10 Jun, 2024, 10:34: AM
CBSE 10 - Maths
Asked by deepikaselvam2009 | 20 Feb, 2024, 20:57: PM
CBSE 10 - Maths
Asked by keshavsinghalhapur | 16 Jan, 2024, 20:46: PM
CBSE 10 - Maths
Asked by keshavsinghalhapur | 15 Jan, 2024, 10:56: AM
CBSE 10 - Maths
Asked by skandachiranjeevin | 06 Dec, 2023, 19:08: PM
CBSE 10 - Maths
Asked by prassanna.j | 13 Nov, 2023, 23:24: PM
CBSE 10 - Maths
Asked by latayadav23 | 17 Oct, 2023, 20:39: PM
CBSE 10 - Maths
Asked by ananya_monica | 28 Sep, 2023, 19:07: PM
CBSE 10 - Maths
Asked by simmysingh1aug | 20 Sep, 2023, 22:20: PM
CBSE 10 - Maths
Asked by bkhaiwangkonyak | 07 Mar, 2023, 16:35: PM