Question

Find an explicit rule for the nth term of the sequence.

7, 21, 63, 189, ...

Answer 1

an = 7 • 3n

an = 7 • 3n - 1

an = 3 • 7n - 1

an = 7 • 3n + 1

Answer 2

is the first choice \(a_n=7 \times 3^n\) ??

Answer 3

yeah i guess. 7 x 3n is the same thing

Answer 4

3n and 3^n are not the same thing...

Answer 5

well then is is actually 3n the way it is written

Answer 6

no it is 3^n

Answer 7

yesss.

Answer 8

so, do you notice, in that sequence that if you multiply each term by 3, you get the next term ?

Answer 9

yes

Answer 10

so would it be 7 x 3^n +1

Answer 11

lets check!
for n=1
7x 3^(1+1) = 7*3^2 does not equal 7
because n=1 implies first term which should be 7.
so, its not 7. 3^(n+1)

Answer 12

so then it has to be 7 x 3^n

Answer 13

lets check again!
for n=1,
7 x 3^1 =.... ?

Answer 14

21

Answer 15

n=1 means first term, it should come out to be 7.
does it ?

Answer 16

yea so would it =147

Answer 17

???????????????

Answer 18

where does 147 come from ?? :O

Answer 19

idk know just forget it. so the first term is 7, so would A be the answer

Answer 20

for which of the 4 :
an = 7 • 3n

an = 7 • 3n - 1

an = 3 • 7n - 1

an = 7 • 3n + 1

is the 1st term =7 ??
you can find out just by plugging, n=1.

Answer 21

an= 7x 3n

Answer 22

a1 = 7x 3^1 = 21 does not =7
so its not 7x3n

Answer 23

7 x 3n-1

Answer 24

yes :)

Answer 25

thnx

Answer 26

welcome :)