Question

Write a rule for the nth term of the geometric sequence. 5, 10, 20, 40, ...

Answer 1

@TheViper

Answer 2

n=2(n-1) i want to say thats it

Answer 3

then again how will that help?

Answer 4

@NickR what do i substitute

Answer 5

\[a_{n}=5*2^{n-1}\]

Answer 6

what's that?

Answer 7

what's the actual formula?

Answer 8

@myko

Answer 9

ah forgot the 5

Answer 10

thats your answer

Answer 11

can someone plz just tell me the formula and what to substitute

Answer 12

myko gave you the answer

Answer 13

is that the answer or formula?

Answer 14

that is your rule for the function

Answer 15

how did he find it?

Answer 16

what's the formula?

Answer 17

well you can see that its exponential, and is 2* the number before it, and starts at 5 so...

Answer 18

there really isnt a general formula

Answer 19

plz just explain to me again how he got the answer ? also what's the answer?

Answer 20

@NickR

Answer 21

you can see that the sequence is exponential right

Answer 22

exponential? what's that?

Answer 23

means that it doesnt increase at a constant rate

Answer 24

alright. in this sequence the number is multiplied by 2to get the next number.

Answer 25

correct

Answer 26

right?

Answer 27

you got it because i need to go

Answer 28

what do i have to do next?

Answer 29

and the initial number is 5 so its 5*2(n-1)
the general equation for this equation is \[a _{n}=a _{1}*d(n-1)\]

Answer 30

where a1 is your first term 5
and d is how many times its multiplied 2

Answer 31

so its 10(n-1) as the answer

Answer 32

@NickR

Answer 33

@satellite73

Answer 34

\[a_n=5(2)^{n-1}\]

Answer 35

\[a_n=a(r)^{n-1}\]
a=first term
r=ratio