Question

3, -24, 192, ... Find the 19th term:​

Answer 1

Explanation:

a

n

​

=ar

n−1

a

3

​

=ar

2

=24...(1)

a

6

​

=ar

5

=192...(2)

dividing (2) by (1) we get

ar

2

ar

5

​

=

24

192

​

r

3

=8⇒r=2

From (1)

ar

2

=24

a=

2

2

24

​

=6

∴a

10

​

=(6)(2)

10−1

=3072