Question

In a A. P, if 7a_{7} = 11a_{11} then find 18th term.

Answer 1

Given,

$7a_{7} = 11a_{11}$

We know that ,
a7 = a + ( 7-1)d = a+6d
a11 = a + ( 11-1)d = a+10d

Now,

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

We know that,
18th term = a + (18-1)d = a+17d

So, 18th term of this A. P is 0

Answer 2

HEY.......
HERE IS U R ANSWER
===================================

A/Q
7 (a7) = 11(a11)
7 ( a + 6d) = 11 (a + 10 d)
7a + 42d = 11 a + 110 d
4a + 68d = 0
a + 17d = 0

As a 18 = a + 17d
so from above a18 = 0
===================================
HOPE IT WILL HELP YOU A LOT....
THANKU.....