## anonymous 4 years ago Is the sequence geometric? 2, 6, 18, 54,... A. yes B. no

1. Mertsj

A

2. amistre64

if 6/2 = 54/18 then yes

3. amistre64

otherwise no

4. Mertsj

You always multiply by 3 to get the next term

5. anonymous

Okay thanks! I am writing that in my notebook so I do not forget that! :)

6. amistre64

the multiply by 3 part, or the dividing last terms part?

7. anonymous

Both!

8. amistre64

given a sequence$a_1,a_2,a_3,a_4,...a_n,a_{n+1}$we can determine if its geometric by taking the ratio any 2 terms that are next to each other.$\frac{a_2}{a_1}=\frac{a_7}{a_6}=\frac{a_{n+1}}{a_n}$

9. amistre64

of course it should equal if you go the other way to$\frac{a_1}{a_2}=\frac{a_n}{a_{n+1}}$but it just wont be the correct ratio