Question

HELP WILL GIVE MEDAL
Find an equation for the nth term of the sequence.

-4, -16, -64, -256, ...

Answer 1

a = -4
common ratio = r = -16/-4 = 4

nth term = ar^n = -4 * (4)^n = -4^n+1

for first term n = 0, for second n = 1 and so on

if you want to use 1 as first term

-4^n

Answer 2

so an=-4x4^n-1?

Answer 3

For case of first term has n = 1

Answer 4

im confused now

Answer 5

ohh you are ssayin an=-4x4^n because n=1

Answer 6

This is a geometric series, you multiply each time times a constant in our case 4.

you can use this formula

r = x_{n+1} / x_{n}

x indicate the term

a = first term

r is the ration between 2 consecutive terms

to find the term a_{n}

x_{n}= ar^n-1

Answer 7

oh so i was right the second time

Answer 8

I told you that it depends on how you count
zero is the first term or 1 is the first term.

Answer 9

To me, I used to count from zero.

Answer 10

I think it is 0

Answer 11

See the formula:

x_{n} = ar^(n-1)

put n = 1

x_{1} = ar^0

x_{n} = ar^n

put n = 0

x_{n} = ar^0

Answer 12

Oh i definitley got the answer now i get it, it is an=-4x4^n-1 thanks!

Answer 13

You're welcome.