Answers

2016-03-17T16:26:48+05:30
Let 1st term & common difference of the A.P. be respectively a & d. according to question

 7 ( a + 6d) = 11 ( a + 10 d) 
⇒11a + 110 d = 7a + 42 d 
⇒ 4a + 68 d = 0  4(a + 17 d) = 0 

⇒ a + 17d = 0 
⇒ 18th term⇒ a + 17 d = 0
0
2016-03-17T16:29:36+05:30