Respuesta :

Remember in a geometric sequence you multiply if it is increasing if it is decreasing it is a number less than 1
Ina arthritic sequence you add if it is increasing if it is decreasing you add by a negative number
This sequence is geometric it is being multiplied by 1/2

A geometric sequence is characterized by a common ratio.

The sequence is a geometric sequence

The sequence is given as:

18,9,9/2,9/4,9/8

Divide the second term by the first term to determine the common ratio (r)

[tex]r = 9 \div 18[/tex]

[tex]r = \frac 12[/tex]

Divide subsequent terms by the previous term;

If the result is the same as [tex]r = \frac 12[/tex], then the sequence is geometric

So, we have:

[tex]r =\frac 92 \div 9[/tex]

[tex]r = \frac 12[/tex]

[tex]r =\frac 94 \div \frac 92[/tex]

[tex]r = \frac 12[/tex]

[tex]r =\frac 98 \div \frac 94[/tex]

[tex]r = \frac 12[/tex]

Notice that the common ratio (r) is the same for all quotients.

Hence, the sequence is a geometric sequence

Read more about geometric sequence at:

https://brainly.com/question/1509142