Question

I don't get this at all!!
Which describes the type of sequence in -99, -88, -66, -55....?
a. both arithmetic and geometric
b. geometric
c. arithmetic
d. neither arithmetic nor geometric
Please explain as well! Thanks :)

Answer 1

how do you test if a sequence is arithmetic?

Answer 2

well i know that they don't have a constant pattern haha that's all i got :/

Answer 3

You're right


The more formal way to say this is that there isn't a common difference

Answer 4

notice that the difference between -99 and -88 is 11, but the difference between -88 and -66 is 22

Answer 5

so what's the answer then? I have nooo idea at all?? so it's not arithmetic... but is it geometric?? idk.. :O

Answer 6

is there a common ratio?

Answer 7

no i don't think so..

Answer 8

we can test this by saying

-55/(-66) = 5/6

but

-66/(-88) = 3/4


So there isn't a common ratio

Answer 9

sooo it's neither geometric OR arithmetic? I'm getting super confused,.. :(

Answer 10

yes, it's "neither arithmetic nor geometric "

Answer 11

so choice D

Answer 12

yay thank you @jim_thompson5910 are you like really good at math or something??

Answer 13

yes I am, you're very welcome

Answer 14

Haha hi again @ParthKohli and thank you so much @jim_thompson5910 haha do you two know each other? lol and what's a harmonic sequence??

Answer 15

I saw you were typing @ParthKohli but i didn't see anything pop up on my screen..did you reply?? or no? haha

Answer 16

It appears s/he left, what's your question?

Answer 17

oh haha i was wondering wat a harmonic sequence was but @ParthKohli said it wasn't a harmonic one hahhaa :)

Answer 18

oh ok, yeah I was questioning that myself as well since the harmonic sequence involves fractions