ICSE Class 10 Answered
The sum of first 7 terms of an AP is 49 and that of first 17 terms of it is 289 . Find the sum of first n terms .
Asked by debabratap261 | 23 Mar, 2019, 08:49: AM
Sum of 7 terms = (7/2) [ 2a + 6 d ] = 49 or a+3d = 7 ....................(1)
Sum of 17 terms = (17/2) [ 2a + 16 d ] = 289 or a+8d = 17 ...................(2)
By solving eqn. (1) and (2), we get a = 1, d = 2
Hence sum of n terms (n/2)[2+(n-1)2 ] = n2
Answered by Thiyagarajan K | 23 Mar, 2019, 09:30: AM
Application Videos
Concept Videos
ICSE 10 - Maths
Asked by ag1106511 | 17 Jul, 2024, 00:41: AM
ICSE 10 - Maths
Asked by astonfern123 | 14 Jul, 2024, 20:01: PM
ICSE 10 - Maths
Asked by anjumnahida176 | 23 Jun, 2024, 15:29: PM
ICSE 10 - Maths
Asked by rupalipatange0 | 13 Jun, 2024, 20:36: PM
ICSE 10 - Maths
Asked by tanushreetanu46t | 12 Jun, 2024, 22:59: PM
ICSE 10 - Maths
Asked by varucreations16 | 12 Jun, 2024, 22:45: PM
ICSE 10 - Maths
Asked by varucreations16 | 09 Jun, 2024, 15:02: PM
ICSE 10 - Maths
Asked by rakesh_shukla2006 | 06 Jun, 2024, 12:55: PM
ICSE 10 - Maths
Asked by raghutangi04 | 30 May, 2024, 19:20: PM