Question

The first three terms of a geometric sequence are 27, -9 and 3.
What is the value of the common ratio, r?

Answer 1

Answer:

Step-by-step explanation:

Now sum of infinite series is  

a

1

−

r

and if first three term are removed, fourth term becomes the first term i.e. first term becomes  

a

r

3

and

sum of infinite series becomes  

a

r

3

1

−

r

As  

a

1

−

r

=

27

×

a

r

3

1

−

r

27

r

3

=

1

or  

r

3

=

1

27

and  

r

=

1

3

and hence

Common ratio is  

1

3