Question

Is it geometric?

Answer 1

what is the pattern, can you tell me?

Answer 2

take 0.8/1.6 what does it give

Answer 3

It decreases by .2 each time?

Answer 4

0.8 - 0.2 = 0.4 ? are you sure it decrease by 0.2 ?

Answer 5

I mean't .4

Answer 6

are you adding/subtracting, OR multiplying/dividing ?

Answer 7

Do I go 1.6+0.4 to figure out if it is adding and same for -, x, and /?

Answer 8

i already gave you a hint

Answer 9

Divide?

Answer 10

yes

Answer 11

So geometric?

Answer 12

yes

Answer 13

why is it a geometric?

Answer 14

Cause you divide by 0.4 to get the next number

Answer 15

hmm not quite

Answer 16

And when you divide or multiply it's geometric.

Answer 17

And if you add or subtract it's arithmetic

Answer 18

Right?

Answer 19

see the pattern

Answer 20

we are not diving by 0.4

Answer 21

Whenever you aren't clear, try to see if there is an equivalent common difference between all of the terms.

For geometric sequence:
\(\large\color{black}{ \displaystyle {\rm d}=a_{n+1}-a_n }\)
(d, is the difference. IT MUST BE EQUIVALENT BETWEEN ANY TERM AND THE ONE AFTER IT)

If the difference isn't always equivalent, then it is not arithmetic.
For example in your sequence:
\(\large\color{black}{ \displaystyle {\rm d}=a_{2}-a_{1}=0.8-1.6=-0.8 }\)
and, \(\large\color{black}{ \displaystyle {\rm d}=a_{3}-a_{2}=0.4-0.8=-0.4 }\)

So the difference aren't equivalent, and therefore it can't be arithmetic sequence.

Answer 22

Yes. But was I right about what I said above

Answer 23

we are dividing by 2 to get the next term

Answer 24

yes, geometric is correct

Answer 25

in this case))

Answer 26

Okay thank you

Answer 27

correct but wrong on the reason
we are dividing by 2 not 0.4

Answer 28

for geometric sequence (in general), you must have a ratio, or a proportional relationship betwen the terms.

\(\large\color{black}{ \displaystyle {\rm r}=\left(a_{n+1}\right) \div \left(a_{n}\right) }\)

for all terms.

Such that:
\(\large\color{black}{ \displaystyle {\rm r}=\left(a_{2}\right) \div \left(a_{1}\right)=\left(a_{3}\right) \div \left(a_{2}\right)=\left(a_{4}\right) \div \left(a_{3}\right) =~...~= ~\left(a_{n+1}\right) \div \left(a_{n}\right) }\)

Answer 29

I know! You have done told me..

Answer 30

Okay thank you Solomon

Answer 31

after 3 d0ts, it is supposed to be

\(\large\color{black}{ ...=\left(a_{n+1}\right) \div \left(a_{n}\right) }\)

Answer 32

I will write that down

Answer 33

sure.... or you can find a tutorial online that explains better and in detail

Answer 34

or a video.... I think absolutely everyone explained what it is already;) Internet is vast!

Answer 35

you welcome...