Question

write a possible explicit rule for the nth term of each sequence

0.8 , 1.6 , 3.2 , 6.4 , 12.8

Answer 1

do you find any pattern in that sequence ?

Answer 2

Have you considered successive ratios?

1.6 / 0.8 = 2

3.2 / 1.6 = ??

Hunt around a little.

Answer 3

no , i dont get how to do this one at aall . :0

Answer 4

I think the detective tkunny was on to something there.

Answer 5

there's a pattern! if you see each term is 2 times the previous term!

Answer 6

the hint was ratio

Answer 7

ohkay i see what you mean finally about the term is 2 times the previous term , but now what ..

Answer 8

is that the answer? loll this is so wackkkk to me.

Answer 9

Write an explicit rule. You do not have "the answer" until you write the rule. Write!

Answer 10

The first rule would be never to say that again - or think it. Just let it go.

What's the first element in the sequence?
How can we get to the second element from the first?

Answer 11

by multiplying by 2 every time you get an answer. ?

Answer 12

common ratio(r) is the ratio between consecutive terms, here r =2

1st term = a1 = 0.8
use the general formula
\(a_n = a_1 r^{n-1} \)
just plug in values!

Answer 13

so its an=0.8 2n-1?

Answer 14

yes,
\(a_n = 0.8 (2)^{n-1} = (0.8/2) (2^n) =0.4 (2)^n \)

Answer 15

an= 0.8(2) n-1 is the main answer tho right? thats all i have to put? or the other stuff to?

Answer 16

with a little hat : 0.8 * (2^(n-1))

Answer 17

?

Answer 18

\(a_n = 0.8 (2)^{n-1}\)
is the correct answer
and
\(a_n = 0.4 (2)^{n}\)
is the simplified form
you can put either of them

Answer 19

he's right.
my intervention is to point out that : 0.8 (2) n-1
is not going to be understood by a "robot" as \(0.8 (2^{n-1})\). if you write text, you have to use the '^' (hat) which means "to the power".