Question

PLEASE HELP WILL MEDAL


Determine if the sequence is arithmetic or geometric. Then find the next term in the sequence. Select all that apply.

1, -4, 16, -64, …



arithmetic


geometric


128


256


Find the common ratio, r, in the following geometric sequence.

2, 6, 18, 54, …



3


-3


4


9

Answer 1

@welshfella can you help ?

Answer 2

for the first one try dividing the first term by the second then 3rd by 2nd etc and see if you get the same result
first / 2nd = 1 / -4 = 1/4
2nd / 3rd = -4/16 = ?

Answer 3

if these are all the same then we have a common ratio and the series is geometric.

Answer 4

* that is -1/4 not 1/4

Answer 5

-4/16 = what?

Answer 6

-0.25?

Answer 7

yes or -1/4
and finally 16/-64 = -1/4

so its geometric

Answer 8

Oh okay, thank you! :)

Answer 9

Oh - SIlli me!! we should be doing the opposite division - like -4 / 1 = -4
The common ratio is -4 not -1/4.

- the common ration multiplies each term to get the next
so the next term in series is -64 * -4 = 256

Answer 10

for second question
r = 6/2

Answer 11

yw

Answer 12

check this is true by dividing the others

18/6 =
54/18 =

Answer 13

the general form of a geometric series is
a, ar , ar^2, ar^3 , ar^4.....

a is the first term and r = common ratio

Answer 14

gotta go right now

Answer 15

Thanks so much! :)