The sum of fourth and twelfth term of an arithmetic progression is 20. What is the sum of the first fifteen terms of that arithmetic progression?
Created: 6 years ago |
Updated: 3 years ago
best des
ধরি, ধারাটির ১ম পদ a এবং সাধারণ অন্তর d
a + 3d + a + 11d = 20
2a + 14d = 20
S15 = 15/2 { 2a + ( 15 - 1) d }
= 15/2 × ( 2a + 14d)
= 15/2 × 20
= 150
Md Azizur Rahman
Founder of Satt
Related Question
View More
Created: 6 years ago |
Updated: 3 weeks ago
Created: 6 years ago |
Updated: 3 weeks ago
Created: 6 years ago |
Updated: 3 weeks ago
Created: 6 years ago |
Updated: 2 days ago
Created: 6 years ago |
Updated: 3 weeks ago
Promotion
Download Our Mobile Apps
