Question

1. The following is a geometric sequence.
-18, 12, -8, 5, ….
True or false?

Answer 1

Do you know how to find first and common ratio from the geometric sequence given??

Answer 2

first term I mean..

Answer 3

Try to check the condition
\[\frac {12} {-18} = \frac {-8} {12}=\frac {5} {-8}\]
If it is true, you have geometric sequence.

Answer 4

The first two equal each other but the last one isn''t, so this is false?

Answer 5

You are right.

Answer 6

thank you!

Answer 7

geometric sequence general formula is
\[a_{n}=a_{1}r^{n-1}\]
find the common ratio
12/-18=-2/3
-8/12=-2/3
5/8=5/8
since the common ratio is not same so it is not geometric