Question

What is the 7th term of the geometric sequence where a1 = -4,096 and a4 = 64?

Answer 1

@amistre64

Answer 2

@Hero

Answer 3

I don't know how to do this xD I've tried everything I knew :P

Answer 4

is that all of the numbers?

Answer 5

yep

Answer 6

\[an = a1rn-\]

Answer 7

ok uhm i dont know this but ill figure it out

Answer 8

64=-4096+d(4-1)

Answer 9

:p

Answer 10

I don't know what to do, I keep getting

Answer 11

1386.666667

Answer 12

as my d

Answer 13

there is a similairty herer with some euqations http://openstudy.com/study#/updates/4fb0905fe4b059b524fcbb73

Answer 14

:o

Answer 15

I already read that :P

Answer 16

Problem is, I need to know how to do it myself xD

Answer 17

I didn't understand that persons way :p

Answer 18

@aaronq

Answer 19

https://www.khanacademy.org/math/precalculus/seq_induction/precalc-geometric-sequences/v/geometric-sequences

Answer 20

:o

Answer 21

this is calculaus?

Answer 22

Uhhh, this is... Algebra xD

Answer 23

lol i have no idea but that guy is good at explaining i watch him all the time

Answer 24

Problem with this god damn school.

Answer 25

is that their formula, and other peoples formula is different

Answer 26

i had to do geomtric sequences too in algerbra 2 but i just noticed it s part of calculus

Answer 27

Its super annoying xD

Answer 28

lol!

Answer 29

mhmm....

Answer 30

anyone~~~~~~

Answer 31

@perl

Answer 32

I really don't want to confuse you don't know what formula you have

let me know if you have any questions about my response

Answer 33

@amistre64

Answer 34

:p EQUATIONS!!!

Answer 35

And for the equations I used

Answer 36

I 1st used the Arithmetic one

Answer 37

to get d

Answer 38

triciall prolly has a good bead on it

Answer 39

:o

Answer 40

a1 = -4,096 and a4 = 64

a2 = a1 r
a3 = a1 rr
a4 = a1 rrr

so; 64 = -4096r^3, find r

Answer 41

a7 = a1 r^6 ...

Answer 42

sorry xD I accidentally x'd out of open study :p

Answer 43

to find r, don't you use the arithmetic series formula/equation?

Answer 44

geometric sequence the terms differ by a common ratio r
the first term is a1 the 2nd term is a1* r the next term is (a1r)*r etc
the nth term is determined by a1*r^(n-1)

Answer 45

of course not, why would you do that for a geometric sequence?

Answer 46

then how do I find r xD

Answer 47

i already showed you, all yo ahve to do is read it ...

Answer 48

oh... I just noticed, oh :p

Answer 49

what we really want is r^6; (r^3)^2 so if we wanted to get fancy, we would just find r^3 and square it

Answer 50

right....

Answer 51

64 = -4096 r^3

a7 = -4096 (r^3)^2

Answer 52

mmk :D

Answer 53

I can't think today xD

Answer 54

is r 0.25?

Answer 55

xDDDDDDDD

Answer 56

hmm, it does actually

Answer 57

may I ask why I was issued a warning....

Answer 58

xD

Answer 59

ok...

Answer 60

its not 0.25

Answer 61

is it -0.25? xD

Answer 62

Cuz I got -64 when I put just 0.25 in the equation you gave me

Answer 63

i forgot the negative too lol r^6 is a postive value so i wasnt really concerned

Answer 64

ah

Answer 65

so its 1!

Answer 66

HAHA!

Answer 67

SUCCESS!

Answer 68

-4096 (.25)^6

-1

Answer 69

NOOOOOo

Answer 70

ITS -1???

Answer 71

NUUUUU xDDD

Answer 72

2late4m3

Answer 73

you was close, foiled by a negative

Answer 74

curse you -!

Answer 75

I clicked on 1 and submitted

Answer 76

fish nuggets... :p

Answer 77

oh well xD Thank you everyone :3

Answer 78

I SHALL TREASURE THIS EXPERIENCE GREATLY! OTHER THAN GETTING NEGATIVES WRONG.